Wikipedia articles should cite reliable sources for their information.
(See some example citations.)
 | This guideline is a part of the English Wikipedia's Manual of Style. Editors should generally follow it, though exceptions may apply. Substantive edits to this page should reflect consensus. When in doubt, discuss first on this guideline's talk page. |
Why are references important?
| Manual of Style (MoS) |
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- To credit a source for providing useful information.
- To provide more information or further reading.
- To enhance the accuracy and credibility of articles.
- To facilitate quick and efficient verification of facts, especially in cases of vandalism.
- To minimise the occurrence of editorial disputes, or assist in resolving those which arise.
- To enhance the overall credibility and authoritative character of Wikipedia.
- To avoid claims of plagiarism or any other forms of intellectual dishonesty.
When you add content
For all of the above reasons, if you add information to an article which you gleaned from a specific external source, please cite where you got your information. If you can properly format your citation, that's great! If not, others can re-format it for you, as long as you provide all the information necessary to find the original source.
In general, even if you are writing from memory, you should actively search for authoritative references to cite. (If you are writing from your own knowledge, then you should know enough to identify good references that the reader can consult on the subject—you will not be around forever to answer questions.) The main point is to help the reader and other editors, which is why you should try to go beyond those sources you happened to use yourself.
The need for citations is especially important when writing about the opinions held on a particular issue. Avoid weasel phrases like, "Some people say..." Instead, find a specific person or group who holds that opinion, mention them by name, and give a citation to some place where they can be seen or heard expressing that opinion.
Just because a statement is referenced does not mean that it is appropriate or conveys an accurate impression. As implicitly described in the official NPOV policy, even if a citation is from a reputable source, it should provide the reader the gist of the research on a certain subject and not merely carefully selected or out-of-context quotes to support a certain point of view.
Remember that Wikipedia is not for your opinions or for original research.
When there is a factual dispute
Disputed information which, if verified, would remain in an article, should be placed on the article's talk page—this gives other users the opportunity to find sources to support it, in which case the information could be re-inserted into the article proper.
When there is no factual dispute
Reference anyway. There might be a dispute in the future, and there are many other reasons to have good citations, as mentioned in the introduction.
Adding general or specific citations to articles which lack them (whether or not you wrote it) is an excellent way to contribute to Wikipedia. See Wikipedia:Forum for Encyclopedic Standards and Wikipedia:WikiProject Fact and Reference Check for organized efforts to do this.
Style and how-to
All references should be collected at the end of the article under a ==References== heading. The most important thing is to enter the complete reference information—formatting is a secondary detail. You can quickly insert inline references to web pages by inserting a URL surrounded by single square brackets, although a more complete reference is preferred. For example, [http://en.wikipedia.org/wiki/Wikipedia:Cite_sources] renders as [1].
Citations in the text (inline citations) and at the end
Under the ==References== heading, list the complete reference information as a bulleted (*) list, one per reference work.
In addition to listing a reference at the end, you may also choose to embed a pointer to a particular reference within the article text. To do this, cite references parenthetically as "(Author-Last-Name, Year)"—this is called Harvard referencing. Use the original publication year for a re-published work. If the cited information is not easy to find with just that information (for example, if it is a poorly indexed topic in a large book), add chapters ("chap. 3") or pages ("p. 15" or "pp. 12–23") after the year (separating the two with a comma). When a reference is used as a noun, put the year in parentheses, for example "Milton (1653) says ..." For two authors, use (Author1 & Author2, Year); for more authors, use (Author1 et al., Year).
It is often preferable to have a few general references to authoritative overviews of a subject, such as textbooks and review articles, rather than a large number of specific in-text citations for individual facts.
On the other hand, in-text references can be very useful if there is a long list of references and it is not clear which one the reader should consult for more information on a specific topic. In-text citations can also be valuable if there is doubt or disagreement on some point—you can parenthetically indicate exactly what source made a particular claim. (Articles that involve strong opposing viewpoints may need to have numerous in-text citations for this reason.)
An example citation style
Formatting of a Wikipedia article reference list is a secondary detail, and there is currently no consensus on a precise prescribed citation format in Wikipedia. Therefore, if you already use a particular citation style, especially the preferred style by scholars in a field related to the article you are editing, please use the citation style of your choice. However, if you cannot decide on what style to use or if you do not know what information to include, an example style is provided at:
Citation templates
Templates have been created in order to make the example citation style easier to use. These are in the process of being expanded to cover all categories defined above. Whether they are preferable to "plain-text" citations, as above, however, is left to the writer's discretion. See Wikipedia:Template messages/Sources of articles/Generic citations.
WikiBib is a simple bibliography maker written in javascript that has most of these templates built in.
Numbered footnotes for external citations
Footnotes are sometimes useful for relevant text that would distract from the main point if embedded in the main text, yet are helpful in explaining a point in greater detail. Such footnotes can be especially helpful for later fact-checkers, to ensure that the article text is well-supported. Thus, using footnotes to provide useful clarifying information outside the main point is fine where this is needed.
Footnotes can also be used to simply cite sources, and there are some styles which do so.
The current best practice for automatically numbered footnotes is described at Wikipedia:Footnote3 (the {{ref|...}} / #{{note|...}} system). Note however:
- This type of footnote requires external links (URL's) in single square brackets used on the same page to be named (which is good practice too, but has to be checked for the page you're working on when introducing this footnote system)
- Several other "numbered footnote" systems have been proposed and/or implemented, and may still be encountered on some wikipedia pages: see "see also" section on Wikipedia:Footnote3 that links to several of these.
Citing Wikipedia
Inside a Wikipedia article, reference another Wikipedia article simply by surrounding its name with two square braces, for example, [[Wikipedia]]. If this does not flow, use a renaming reference, for example, [[Wikipedia|Wikipedia's contents]] (also known as pipe-linking as the vertical bar symbol is called a "pipe"). This is not an external reference, but it is very useful for readers. In general, only create a link to another Wikipedia article the first time a reference is made (though occasional exceptions for consistency or because it is a long article can be justified); otherwise, a page may be full of links and become difficult to read for some people.
Avoid duplicating references on a single topic unnecessarily — put the references in the most specific Wikipedia article on that topic, and not in other articles that link to that article. (Thus, for example, this article does not cite the APA, since there is a whole Wikipedia article on just that subject.)
For suggestions on how to cite Wikipedia in other works, see Wikipedia:Citing Wikipedia
References
- Concordia Libraries (Concordia University). Citation and Style Guides. Retrieved December 28, 2004. (This provides a list of common citation styles.)
- Citation Styles Handbook: APA
- Citation Styles Handbook: MLA
- APA Style.org
- Using American Psychological Association (APA) Format (Updated to 5th Edition)
- Citing Electronic Documentation (APA, Chicago, MLA)
- The Columbia Guide to Online Style
- Psychology with Style: A Hypertext Writing Guide
- A Guide for Writing Research Papers Based on Modern Language Association (MLA) Documentation
- AMA Citation Style
- Chicago/Turabian Documentation
- Citation Guide - Turabian (.PDF file)
- General Guidelines for Citing Government Publications
- Guide to Citation Style Guides
- Sociology style (ASR)
- Uniform Requirements for Manuscripts Submitted to Biomedical Journals
- American Chemical Society reference style guidelines