Wikipedia:Citing sources

It has been suggested that this project page be merged with Wikipedia:Manual of Style/Footnotes and Help:Footnotes. (Discuss)

This page documents an English Wikipedia content guideline. It is a generally accepted standard that editors should attempt to follow, though it is best treated with common sense, and occasional exceptions may apply. Any substantive edit to this page should reflect consensus. When in doubt, discuss first on the talk page.

Shortcuts: WP:CITE WP:REF

Citations, frequently referred to as references, are an important part of any Wikipedia article, serving to identify the reliable sources on which the information in the article is based. In most cases, citations for specific pieces of information contained in an article are given in the form of footnotes, although they can also appear within the body of an article.

Wikipedia's Verifiability policy describes when sources should be cited and what kind of sources are considered reliable. It requires inline citations for any material challenged or likely to be challenged, and for all quotations, anywhere in article space. However, editors are encouraged to provide citations for all information added to Wikipedia.

This page contains information on how to place and format citations. Each article should use the same citation method throughout. If an article already has citations, adopt the method in use or seek consensus on the talk page before changing it. While you should try to write citations correctly, what matters most is that you provide enough information to identify the source. Others will improve the formatting if needed.

Types of citation

A full citation fully identifies a reliable source and, where applicable, the place in that source (such as a page number) where the information in question can be found. For example: Rawls, John. A Theory of Justice. Harvard University Press, 1971, p. 1. This type of citation is usually given as a footnote, and is the most commonly used citation method in Wikipedia articles.

An inline citation means any citation added close to the material it supports, for example after the sentence or paragraph, normally in the form of a footnote.

A general reference is a citation to a reliable source that supports content, but is not displayed as an inline citation. General references are usually listed at the end of the article in a References section. They may be found in underdeveloped articles, especially when all article content is supported by a single source. They may also be listed by author alphabetically in a References section in more developed articles as a supplement to inline citations.

A short citation is an inline citation that identifies the place in a source where specific information can be found, but without giving full details of the source – these will have been provided in a general reference. For example: Rawls 1971, p. 1. This system is used in some articles; the short citations may be given either as footnotes, or as parenthetical references within the text.

In-text attribution means saying within the article text itself (not as a mere footnote) where particular statements come from. This is done especially with statements of opinion, uncertain facts, and quotations. Usually the in-text attribution does not specify full details of the source text – this is done with a footnote in the normal way. For example: According to John Rawls,^[5]... See In-text attribution below.

When and why to cite sources

By citing sources for Wikipedia content, you enable other editors and readers to verify that the information given is supported by reliable sources, thus improving the credibility of Wikipedia and showing that the material is not original research. You also help readers find additional information on the subject; and you avoid committing plagiarism (by giving credit to the source of your words or ideas).

In particular, sources are required for material that is challenged or likely to be challenged – if reliable sources cannot be found for challenged material, it is likely to be removed from the article. Sources are also required when quoting someone, with or without quotation marks, or closely paraphasing a source. However, the citing of sources is not limited to those situations – editors are always encouraged to add or improve citations for any information contained in an article.

Citations are especially desirable for statements about living persons, particularly when the statements are contentious or potentially defamatory. In accordance with the biography of living persons policy, unsourced information of this type is likely to be removed.

Citations are not used on disambiguation pages (sourcing for the information given there should be done in the target articles). Citations are also often discouraged in the lead section of an article, insofar as it summarizes information for which sources are given later in the article, although such things as quotations and particularly controversial statements should be supported by citations even in the lead.

In a somewhat different sense, and mainly for the avoidance of copyright violation, you need to provide a source when uploading an image.

Making citations

How to place an inline citation

Unless the article uses parenthetical references (see below), inline citations should be added in the form of footnotes. To create a footnote, use the <ref>...</ref> syntax at the appropriate place in the article text, for example:

• Justice is a human invention.<ref>Rawls, John. ''A Theory of Justice''. Harvard University Press, 1971, p. 1.</ref> It...

which will be displayed as something like:

• Justice is a human invention.^[1] It...

It will also be necessary to generate the list of footnotes (where the citation text is actually displayed); for this, see the next section.

As in the above example, citations are normally placed after adjacent punctuation such as periods and commas. For exceptions, see WP:REFPUNC.

The citation should be added close to the material it supports, offering text-source integrity. If a word or phrase is particularly contentious, an inline citation may be added next to that word or phrase within the sentence, but it is usually sufficient to add the citation to the end of the sentence or paragraph, so long as it's clear which source supports which part of the text.

How to create the list of citations

When there are footnote citations (or other footnotes) in the text, it will also be necessary, at or near the bottom of the article, to create a place where the text of those citations is to appear. This is done in a separate section, usually titled "Notes" or "References", and using either the <references /> tag or the {{reflist}} template, for example:

==Notes==

{{reflist}}

The footnotes will then automatically be listed under that section heading. Each numbered footnote marker in the text is a clickable link to the the corresponding footnote, and each footnote contains a caret which links back to the corresponding point in the text.

Repeated citations

For multiple use of the same citation or footnote, you can also use the named references feature, choosing a name to identify the citation, and typing <ref name="name">text of the citation</ref>. Thereafter, the same footnote may be reused any number of times by typing just <ref name=name/>. For more details of this syntax, see WP:NAMEDREFS.

List-defined references

A feature which can reduce the clutter caused by citations in the edit window is list-defined references. This makes it possible for every citation to be written as just a named reference, with the actual text of the citations moved to the notes/references section.

To do this, use the following syntax:

The Sun is pretty big,<ref name="Miller2005p23" /> but the Moon is not so big.<ref name="Brown2006" /> The Sun is also quite hot.<ref name="Miller2005p34" />

==References==
{{Reflist|refs=
<ref name="Miller2005p23">Miller, Edward.''The Sun''. Academic Press, 2005, p. 23.</ref>
<ref name="Miller2005p34">Miller, Edward.''The Sun''. Academic Press, 2005, p. 34.</ref>
<ref name="Brown2006">Brown, Rebecca. "Size of the Moon," ''Scientific American,'' 51(78):46</ref>
}}

which will be displayed like this:

The Sun is pretty big,^[1] but the Moon is not so big.^[2] The Sun is also quite hot.^[3]

References

---

1. ^ Miller, Edward. The Sun. Academic Press, 2005, p. 23.
2. ^ Brown, Rebecca. "Size of the Moon," Scientific American, 51(78):46.
3. ^ Miller, Edward. The Sun. Academic Press, 2005, p. 34.

As with other citation formats, list-defined references should not be added to articles that already have a stable referencing system, unless there is consensus to do so. When in doubt, follow the referencing system used by the first major contributor to employ a consistent style.

Short citations

Some Wikipedia articles use short citations, giving summary information about the source together with a page number, as in <ref>Smith 2010, p. 1.</ref>. These are used together with general references, which give full details of the sources, but without page numbers, and are listed in a separate "References" section. Short citations are used in articles which apply parenthetical referencing (see below), but they can also be used as footnote citations, as described here.

Forms of short citations used include author-date referencing (APA style, Harvard style, or Chicago style), and author-title or author-page referencing (MLA style or Chicago style). As before, the list of footnotes is automatically generated in a "Notes" or "Footnotes" section, which immediately precedes the "References" section containing the general references. Short citations can be written manually, or by using the {{sfn}} or {{harvnb}} templates. (Note that templates should not be added without consensus to an article that already uses a consistent referencing style.) The short citations and general references may be linked so that the reader can click on the short note to find full information about the source. See the template documentation for details and solutions to common problems. For variations with and without templates, see wikilinks to full references. For a set of realistic examples, see these.

This is how short citations look in the edit box:

The Sun is pretty big,<ref>Miller 2005, p. 23.</ref> but the Moon is not so big.<ref>Brown 2006, p. 46.</ref> The Sun is also quite hot.<ref>Miller 2005, p. 34.</ref>

== Notes ==
{{Reflist}}

== References ==
*Brown, Rebecca (2006). "Size of the Moon," ''Scientific American'', 51(78).
*Miller, Edward (2005). ''The Sun''. Academic Press.

This is how they look in the article:

The Sun is pretty big,^[1] but the Moon is not so big.^[2] The Sun is also quite hot.^[3]

Notes

---

1. ^ Miller 2005, p. 23.
2. ^ Brown 2006, p. 46.
3. ^ Miller 2005, p. 34.

References

---

• Brown, Rebecca (2006). "Size of the Moon", Scientific American, 51(78).
• Miller, Edward (2005). The Sun. Academic Press.

Shortened notes using titles rather than publication dates would look like this in the article:

Notes

---

1. ^ Miller, The Sun, p. 23.
2. ^ Brown, "Size of the Moon", p. 46.
3. ^ Miller, The Sun, p. 34.

Since the links are placed manually it is easy to introduce errors such as duplicate anchors and unused references. The script User:Ucucha/HarvErrors will show many related errors. Duplicate anchors may be found by using the W3C Markup Validation Service.

Parenthetical referencing

While most articles use footnote citations as described in the above sections, some articles use a parenthetical referencing style. Here, short citations in parentheses, such as (Smith 2010, p. 1), are placed within the article text itself. Full details of each source used are given in a general reference, e.g. Smith, John. Name of Book. Cambridge University Press, 2010. The general references are listed in alphabetical order, according to the authors' surnames, at the end of the article in a "References" section.

Several forms of short citation are used in Wikipedia; see Short citations above. The inline citation and general reference may be linked using a template (see linking inline and full citations); as with other citation templates, these should not be added to articles without consensus.

This is how it looks in the edit box:

The Sun is pretty big (Miller 2005, p. 1), but the Moon is not so big (Brown 2006, p. 2). The Sun is also quite hot (Miller 2005, p. 3).
== References ==
*Brown, R (2006). "Size of the Moon", ''Scientific American'', 51(78).
*Miller, E (2005). ''The Sun'', Academic Press.

This is how it looks in the article:

The Sun is pretty big (Miller 2005, p. 1), but the Moon is not so big (Brown 2006, p. 2). The Sun is also quite hot (Miller 2005, p. 3).

References

---

• Brown, R (2006). "Size of the Moon", Scientific American, 51(78).
• Miller, E (2005). The Sun, Academic Press.

Text-source integrity

When using inline citations, it is important to maintain text-source integrity. The point of an inline citation is to allow readers and other editors to check that the material is sourced; that point is lost if the citation is not clearly placed. The distance between material and its source is a matter of editorial judgment, but adding text without placing its source clearly can lead to allegations of original research, violations of the sourcing policy, and even plagiarism. Editors should exercise caution when rearranging or inserting material to ensure that text-source relationships are maintained.

The following inline citation, for example, is not helpful, because the reader does not know whether each source supports the material; each source supports part of it; or just one source supports it with the others added as further reading:

N Smith is the UK's best-selling cookery writer and one of the country's highest-earning women.^[1][2][3][4]

Where you are using multiple sources for one sentence, consider bundling citations at the end of the sentence or paragraph with an explanation in the footnote regarding which source supports which point; see below for how to do that.

Bundling citations

You can combine or "bundle" citations between one set of ref tags at the end of a sentence or paragraph, along with an explanation in the footnote for which source supports which part of the text. Citation bundling can be done with long or short footnotes, with or without citation templates. It has multiple benefits:

• it helps readers and other editors see at a glance which source supports which point, maintaining text-source integrity;
• it avoids the visual clutter of multiple clickable footnotes inside a sentence or paragraph;
• it avoids the confusion of having multiple sources listed separately after sentences, with no indication of which source to check for each part of the text, such as this.^[5][6][7][8]
• it makes it less likely that inline citations will be moved inadvertently when text is re-arranged, because the footnote states clearly which source supports which point.

A simple example of citation bundling:

The sun is pretty big, but the moon is not so big. The sun is also quite hot.^[1]

Notes

---

1. ^ For the sun's size, see Miller, Edward. The Sun. Academic Press, 2005, p. 1.
   • For the moon's size, see Brown, Rebecca. "Size of the Moon," Scientific American, 51(78):46.
   • For the sun's heat, see Smith, John. The Sun's Heat. Academic Press, 2005, p. 2.

In-text attribution

In-text attribution is the attribution inside a sentence of material to its source, in addition to an inline citation after the sentence. In-text attribution should be used with direct speech (a source's words between quotation marks); indirect speech (a source's words without quotation marks); and close paraphrasing. It can also be used when loosely summarizing a source's position in your own words. It avoids inadvertent plagiarism, and helps the reader see where a position is coming from. An inline citation should follow the attribution, usually at the end of the sentence or paragraph in question.

For example:

Y John Rawls argues that, to reach fair decisions, parties must consider matters as if behind a veil of ignorance.^[9]

When using in-text attribution, make sure it doesn't lead to an inadvertent neutrality violation. For example, the following implies parity between the sources, without making clear that the position of Dawkins is the majority view:

N Richard Dawkins argues that human beings evolved through natural selection, but John Smith writes that we arrived here in pods from Mars.

Neutrality issues apart, there are other ways in-text attribution can mislead. The sentence below suggests The New York Times has alone made this important discovery:

N According to The New York Times, the sun will set in the west this evening.

Simple facts such as this can have inline citations to reliable sources as an aid to the reader, but normally the text itself is best left as a plain statement without in-text attribution:

YBy mass, oxygen is the third most abundant element in the universe after hydrogen and helium.^[10]

Dealing with unsourced material

If an article is unreferenced you can tag it with the template {{Unreferenced}}, so long as it is not nonsensical or a biography of a living person, in which case request admin assistance.

• If a claim is doubtful but not harmful, use the {{fact}} tag, which will add "citation needed," but remember to go back and remove the claim if no source is produced within a reasonable time.
• If a claim is doubtful and harmful, remove it from the article. You may want to move it to the talk page and ask for a source, unless it is very harmful or absurd, in which case it should not be posted to the talk page either. Use your common sense.
• All unsourced and poorly sourced contentious material about living persons must be removed from articles and talk pages immediately. See Wikipedia:Biographies of living persons and Wikipedia:Libel.

Some general advice

Say where you read it

Don't cite a source unless you've seen it for yourself. Where you want to cite John Smith, but you've only read Paul Jones who cites Smith, write it like this (this formatting is just an example; there are several ways this can be written):

Smith, John. Name of Book I Haven't Seen, Cambridge University Press, 2009, p. 1, cited in Paul Jones (ed.). Name of Encyclopedia I Have Seen. Oxford University Press, 2010, p. 2.

If you first learned of John Smith's book because it was cited in Paul Jones' encyclopedia, but you then actually obtained and read John Smith's book, it is not necessary to give "credit" to any sources, search engines, websites, library catalogs, etc., that led you to Smith's book. You may cite Smith's book directly and solely in that instance.

For a source available in hardcopy, microform, and/or online, omit, in most cases, which one you read. While it is useful to cite author, title, edition (1st, 2d, etc.), and similar information, it generally is not important to cite a database such as ProQuest, EbscoHost, or JStor (see the list of academic databases and search engines) or to link to such a database requiring a subscription or a third party's login. The basic bibliographic information you provide should be enough to search for the source in any of these databases that have the source. Don't add a URL that has a part of a password embedded in the URL. However, you may provide the DOI, ISBN, or another uniform identifier, if available. If the publisher offers a link to the source or its abstract that does not require a payment or a third party's login for access, you may provide the URL for that link. And if the source exists only online, give the link even if access is restricted.

Multimedia

Multimedia material should be referenced just like article text. Citations for a media file should appear on its file page. Image captions should be referenced as appropriate just like any other part of the article. If an infobox or table contains text that needs citing, but the box or table cannot incorporate an inline citation, the citation should appear in a caption or other text that discusses the material. A citation is not needed for descriptions such as alt text that are verifiable directly from the image itself. Material that identifies a source (e.g., the caption "Belshazzar's Feast (1635)" for File:Rembrandt-Belsazar.jpg) is considered attribution and normally does not need further citation.

Avoid scrolling lists

Scrolling lists, or lists of citations appearing within a scroll box, should never be used because of issues with readability, accessibility, printing, and site mirroring. Additionally, it cannot be guaranteed that such lists will display properly in all web browsers. See this July 2007 discussion for more detail.

General reference

A general reference is a citation to a reliable source that supports content, but is not displayed as an inline citation. General references are usually listed at the end of the article in a References section. They may be found in underdeveloped articles, especially when all article content is supported by a single source. The disadvantage of using general references is that text-source integrity is lost, unless the article is very short. The sourcing policy, Verifiability, requires inline citations for all quotations, and for anything challenged or likely to be challenged.

A general reference looks like this in the edit box:

The Sun is pretty big, but the Moon is not so big. The Sun is also quite hot.

== References ==
*Brown, R (2006). "Size of the Moon", ''Scientific American'', 51(78).
*Miller, E (2005). ''The Sun'', Academic Press.

This is how it looks in the article:

The Sun is pretty big, but the Moon is not so big. The Sun is also quite hot.

References

---

• Brown, R (2006). "Size of the Moon", Scientific American, 51(78).
• Miller, E (2005). The Sun, Academic Press.

Embedded links

Embedded links to external websites should not be used as a form of inline citation, because they are highly susceptible to linkrot. Wikipedia allowed this in its early years—for example by adding a link after a sentence, like this [http://media.guardian.co.uk/site/story/0,14173,1601858,00.html], which looks like this. [1] This is no longer recommended. Raw links are not recommended in lieu of properly written out citations, even if placed between ref tags, like this <ref>[http://media.guardian.co.uk/site/story/0,14173,1601858,00.html]</ref>.

Embedded links should never be used to place external links in the body of an article, like this: "Apple, Inc. announced their latest product..."

Further reading/External links

"Further reading" or "External links" are used as section headings for books, articles, and websites related to the topic that have not been used as sources.

Citation style

There are a number of citation styles. See here for some examples. They all include the same information, but vary in punctuation and the order of the author's name, publication date, title, and page numbers.

Although nearly any consistent style may be used, avoid all-numeric date formats other than YYYY-MM-DD, because of the ambiguity concerning which number is the month and which the day. If used, YYYY-MM-DD format should be limited to Gregorian calendar dates where the year is after 1582.

Style variation and consistency

Citations within each Wikipedia article should follow a consistent style. Editors may choose any style they want. The English Wikipedia does not have a house style, so it need not match what is done in other articles.

If the article you are editing is already using a particular citation style, you should follow it. Do not change it merely for personal preference or cosmetic reasons. If you think the existing citation system is inappropriate for the needs of the article, seek consensus for a change on the talk page. As with issues of spelling differences, if there is disagreement about which style is best, defer to the style used by the first major contributor. If you are the first major contributor to an article, you may choose whichever style you think best for the article.

To be avoided

• Switching between major citation styles, e.g., switching between parenthetical and <ref> tags or between the style preferred by one academic discipline vs. another;
• Adding citation templates to an article that already uses one of the other citation formats listed in this guideline;
• Changing the section heading to or from ==References==, ==Notes==, etc.

Generally considered helpful

• Replacing bare URLs with full bibliographic citations: an improvement because it provides more information to the reader and fights linkrot;
• Replacing some or all general references with inline citations: an improvement because it provides more information to the reader and helps maintain text-source integrity;
• Imposing one style on an article with incompatible citation styles (e.g., where some of the citations are in footnotes and others are parenthetical references): an improvement because it makes the formatting consistent.

What information to include

Examples

Books

Citations for books typically include:

• name of the author(s)
• title of the book in italics
• volume when appropriate
• city of publication is optional
• name of the publisher
• year of publication
• chapter or page number(s) where appropriate
• ISBN where available

Citations for individually authored chapters in books typically include:

• name of author
• the title of the chapter
• name of the book's editor
• name of book and other details as above
• the chapter number or page numbers for the chapter are optional

Journal articles

Citations for journal articles typically include:

• name of the author(s)
• year and sometimes month of publication
• title of the article within quotation marks
• name of the journal in italics
• volume number, issue number, and page numbers (article numbers in some electronic journals)
• DOI and/or other identifiers where available

Newspaper articles

Citations for newspaper articles typically include:

• name of the newspaper in italics
• date of publication
• byline (author's name), if any
• title of the article within quotation marks
• city of publication, if not included in name of newspaper
• page number(s) are optional

Webpages

Citations for World Wide Web pages typically include:

• name of the author(s)
• title of the article within quotation marks
• name of the website
• date of publication
• page number(s) (if applicable)
• the date you retrieved it (required if the publication date is unknown)

Sound recordings

Citations for sound recordings typically include:

• name of the composer(s)/songwriter(s)/script writer(s)
• name of the performer(s)
• title of the song or individual track in quotation marks
• title of the album in italics (if applicable)
• name of the record label
• year of release
• medium (for example: LP, audio cassette, CD, MP3 file)
• approximate time at which event or point of interest occurs, where appropriate

Film, TV, or video recordings

Citations for films, TV episodes, or video recordings typically include:

• name of the director
• name of the producer, if relevant
• names of major performers
• for a TV episode, the title of the episode in quotation marks
• title of the film or TV series in italics
• name of the studio
• year of release
• medium (for example: film, videocassette, DVD)
• approximate time at which event or point of interest occurs, where appropriate

Identifying parts of a source

When citing lengthy sources, you should identify which part of a source is being cited.

Books and print articles

Specify the page number or range of page numbers. Page numbers are not required for a reference to the book or article as a whole. When you specify a page number, it is helpful to specify the version (date and edition for books) of the source because the pagination can change between editions.

Audio and video sources

Specify the time at which the event or other point of interest occurs. Be as precise as possible about the version of the source that you are citing; for example, movies are often released in different editions or "cuts". Due to variations between formats and playback equipment, precision may not be accurate in some cases. However, many government agencies do not publish minutes and transcripts but do post video of official meetings online; generally the subcontractors who handle audio-visual are quite precise.

Links and ID numbers

A citation ideally includes a link or ID number to help editors locate the source. If you have a URL (webpage) link, you can add it to the title part of the citation, so that when you add the citation to Wikipedia the URL becomes hidden and the title becomes clickable. To do this, enclose the URL and the title in square brackets—the URL first, then a space, then the title. For example:

Carr A, Ory D (2006). [http://dx.doi.org/10.1371/journal.pmed.0030496 Does HIV cause cardiovascular disease?] ''PLoS Medicine'', 3(11):e496.

For web-only sources with no publication date you should include a "Retrieved" date instead, in case the webpage changes in the future. For example: Retrieved 2008-07-15.

You can also add an ID number to the end of a citation. The ID number might be an ISBN for a book, a DOI (Digital Object Identifier) for an article, or any of several ID numbers that are specific to particular article databases, such as a PMID number for articles on PubMed. It may be possible to format these so that they are automatically activated and become clickable when added to Wikipedia, for example by typing ISBN (or PMID) following by a space followed by the ID number.

If your source is not available online, it should be available in reputable libraries, archives, or collections. If a citation without an external link is challenged as unavailable, any of the following is sufficient to show the material to be reasonably available (though not necessarily reliable): providing an ISBN or OCLC number; linking to an established Wikipedia article about the source (the work, its author, or its publisher); or directly quoting the material on the talk page, briefly and in context.

Linking to Google Books pages

Google Books allows book pages to be linked to directly, where the book is available for preview. These can be written in a number of ways, with or without citation templates:

• Rawls, John. A Theory of Justice. Harvard University Press, 1971, p. 18.
• Rawls 1971, p. 18.
• Rawls 1971, p. 18.
• Rawls 1971, p. 18.

In edit mode, the URL for p. 18 of A Theory of Justice looks like this:

• Rawls, John. [http://books.google.com/books?id=kvpby7HtAe0C&pg=PA18 ''A Theory of Justice'']. Harvard University Press, 1971, p. 18.

When the page number is a Roman numeral, commonly seen at the beginning of books, the URL looks like this:

• http://books.google.com/books?id=kvpby7HtAe0C&pg=PR17—for page xvii of the same book.

Page links should only be added when the book is available for preview; they will not work with snippet view. No editor is required to add page links, but if another editor adds them, they should not be removed; see the October 2010 RfC for further information.

Convenience links

A convenience link is a link to a copy of your source on a webpage provided by someone other than the original publisher or author. For example, a copy of a newspaper article no longer available on the newspaper's website may be hosted elsewhere. When offering convenience links, it is important to be reasonably certain that the convenience copy is a true copy of the original, without any changes or inappropriate commentary, and that it does not infringe the original publisher's copyright. Accuracy can be assumed when the hosting website appears reliable. Where several sites host a copy of the material, the site selected as the convenience link should be the one whose general content appears most in line with Wikipedia:Neutral point of view and Wikipedia:Verifiability.

Citation templates and tools

For a comparison of citations using templates with citations written freehand, see Wikipedia:Citing sources/Example edits for different methods.

Citation templates are used to format citations in a consistent way. The use of citation templates is neither encouraged nor discouraged. Templates may be used or removed at the discretion of individual editors, subject to agreement with other editors on the article. Because templates can be contentious, editors should not change an article with a distinctive citation format to another without gaining consensus. Where no agreement can be reached, defer to the style used by the first major contributor.

Metadata

Citations may be accompanied by metadata, though it is not mandatory. Most citation templates on Wikipedia use the COinS standard. Metadata such as this allow browser plugins and other automated software to make citation data accessible to the user, for instance by providing links to their library's online copies of the cited works. In articles that format citations manually, metadata may be added manually in a span, according to the COinS specification; or the templates Template:Citation metadata or Template:COinS can be used.

Citation processing tools

• Template:Citation/core – a core template used by other citation templates
• User:Citation bot (formerly DOI bot) – a bot that automatically fixes common errors in individual citations, and adds missing fields
• User:CitationTool – a tool for finding article-level citation errors and fixing them. Not currently functional.
• Reflinks adds titles to bare references and other cleanup

Programming tools

• Wikicite is a free program that helps editors to create citations for their Wikipedia contributions using citation templates. It is written in Visual Basic .NET, making it suitable only for users with the .NET Framework installed on Windows, or, for other platforms, the Mono alternative framework. Wikicite and its source code is freely available; see the developer's page for further details.
  • Wikicite+ is a program based on the original Wikicite source code. It features extra validation, bug fixes, additional cite templates (such as cite episode) as well as tools for stub sorting and more. It is also available for free under the Apache License 2.0 and is open source.
• User:Richiez has tools to automatically handle citations for a whole article at a time. Converts occurrences of {{pmid XXXX}} or {{isbn XXXX}} to properly formatted footnote or Harvard-style references. Written in ruby and requires a working installation with basic libraries.
• pubmed2wiki.xsl an XSL stylesheet transforming the XML output of PubMed to Wikipedia refs.
• RefTag by Apoc2400 creates a prefilled {{cite book}} template with various options from a Google Books URL. The page provides a bookmarklet for single-click transfer.
• wikiciter web interface, does google books, pdf files, beta.

Citation export tools

You can insert a link beside each citation in Wikipedia, allowing you to export the citation to a reference manager, such as EndNote. Just copy this code:

importScript("User:Smith609/endnote.js");

to the end of Special:MyPage/monobook.js. Then, save the page and bypass your browser's cache.

Preventing and repairing dead links

To help prevent dead links, persistent identifiers are available for some sources. Some journal articles have a digital object identifier (DOI); some online newspapers and blogs, and also Wikipedia, have permalinks that are stable. When permanent links aren't available, consider archiving the referenced document when writing the article; on-demand web archiving services such as WebCite (http://www.webcitation.org) are fairly easy to use (see pre-emptive archiving).

Dead links should be repaired or replaced if possible. Do not delete a citation merely because the URL is not working today. Follow these steps when you encounter a dead URL being used as a reliable source to support article content:

1. Confirm status: First, check the link to confirm that it is dead and not temporarily down. Search the website to see whether it has been rearranged.
2. Check for web archives: Several archive services exist; add one of these URLs if available:
   • The Internet Archive and WebCite have billions of archived webpages. See Wikipedia:Using the Wayback Machine and Wikipedia:Using WebCite.
   • The UK Government Web Archive (http://www.nationalarchives.gov.uk/webarchive/) preserves 1500 UK central government websites.
     Note: Most archives currently operate with a delay of ~18 months before a link is made public. As a result, editors should wait ~24 months after the link is first tagged as dead before declaring that no web archive exists. Dead URLs to reliable sources should normally be tagged with {{dead link|date=September 2011}}, so that you can estimate how long the link has been dead.
3. Remove convenience links: If the material was published on paper (e.g., academic journal, newspaper article, magazine, book), then the URL is not necessary. Simply remove it.
4. Find a replacement source: Search the web for quoted text or the article title. Consider contacting the website/person that originally published the reference and asking them to republish it. Ask other editors for help finding the reference somewhere else. Find a different source that says essentially the same thing as the reference in question.
5. Remove hopelessly lost web-only sources: If the source material does not exist offline, and if there is no archived version of the webpage (be sure to wait ~24 months), and if you are unable to find another copy of the material, then the dead citation should be removed and the material it supports should be regarded as unverifiable. If it is material that is specifically required by policy to have an inline citation, then please consider tagging it with {{citation needed}}. It may be helpful to future editors if you move the citation to the talk page with an explanation.

See also

Wikimedia Commons has media related to: Citation needed

How to cite

• Wikipedia:Verification methods – listing examples of the most common ways that citations are used in Wikipedia articles.
• Wikipedia:Citing sources/example style – listing examples of full citations using APA and Harvard referencing techniques.
• Wikipedia:Citing sources/Example edits for different methods – showing comparative edit mode representations for different citation methods and techniques.
• Wikipedia:Citing sources/Further considerations – information of additional interest.
• Wikipedia:Citation templates – a full listing of various styles for citing all sorts of materials.
• Wikipedia:External links – for information about the External links appendix
• Wikipedia:Improving referencing efforts
• Wikipedia:Inline citation
• Wikipedia:Layout#Further reading – for information about the Further reading appendix
• Wikipedia:List of sources
• Wikipedia:Referencing for beginners – a simple practical guide to getting started.
• Wikipedia:Scientific citation guidelines – guidelines for dealing with scientific and mathematical articles.

Citation problems

• Template:Citations missing – template to add where citations are needed
• Wikipedia:A suggested improvement 0001
• Wikipedia:Linkrot – guide to preventing link rot
• Wikipedia:Citation needed – explanation of citation needed template
• Wikipedia:Copyright problems – in case of text that has been copied verbatim inappropriately.
• Wikipedia:WikiProject Citation cleanup – a group of people devoted to cleaning citations
• Wikipedia:Bombardment – an essay regarding the overuse of citations
• Wikipedia:Citation overkill – why too many citations on one fact can be a bad thing
• Wikipedia:Video links – an essay discussing the use of citations linking to YouTube and other user-submitted video sites
• Wikipedia:You don't need to cite that the sky is blue
• Wikipedia:You do need to cite that the sky is blue

Other

• Comparison of reference management software – side-by-side comparison of various Reference management software

Notes

References

Further reading