A citation is:
"A reference providing information about where a particular quotation, text, etc., is to be found; a bibliographical reference."
- Oxford English Dictionary Online, version March 2015
There are many different citation styles which reflect different interests and preferences of disciplines and often publications. If you are unsure which citation style to use, it is best to ask the person you are writing for, such as a professor or journal editor.
You need to cite your sources whenever you:
Cite the source that you used.
In other words, cite only what you have seen. To cite a work that you have not seen or used is dishonest and can perpetuate inaccuracies.
Ideally, you should try to view original sources because other authors may have misrepresented quotes, statistics, ideas or meaning from an original source.
Example: A 2008 article examined the accuracy of citations to a commonly referenced hand surgery study. Of 154 articles that referenced the original study, 63 (41%) had at least one inaccurate reference to this study. The authors concluded: "Care must be taken in referencing biomedical literature, particularly articles that have a potentially profound impact on clinical patient management."
Source: Porrino, J. A., Tan, V., & Daluiski, A. (2008). Misquotation of a commonly referenced hand surgery study. The Journal of Hand Surgery, 33(1), 2–7.
You need to provide enough information for your reader to easily find your sources. The information that you include in a citation depends somewhat on the type of source, e.g. book, book chapter, journal article, or website.
All citations include:
In addition to the information above, citations for BOOKS or BOOK CHAPTERS include:
In addition to the information above, citations for JOURNAL ARTICLES include:
Brown supports a number of citation tools: EndNote, EndNote Online, or Zotero. These resources allow you to automatically store and create citations. Both Zotero and EndNote have their own benefits. To help you decide which one works best for you, look at the MIT Citation Managers comparison guide.