KYVL, the Kentucky Virtual Library, offers this advice regarding citing sources:
Any words, ideas or images that you do not create yourself must be properly credited if you use them in your work. Why? Because you are using someone else's intellectual property.
Citing your information sources acknowledges the origin of your information, and it lends credibility to your work by showing evidence of your research. It demonstrates the authenticity of your information and enables your readers to locate your information sources, should they want to. This includes all types of information sources that you may use, including:
Articles (from print sources or from online article databases)
E-mail or any other correspondence
Non-print media (videotapes, audiotapes, pictures and images)
Software or any digital formats
Whenever you use someone else's intellectual or creative "property," you need to provide a proper citation for your source, in order (1) to give credit to the author or creator and (2) to enable your reader to locate the sources you cite.
A citation is a reference to the source of an idea, information or image. A citation typically includes enough identifying information, such as the author, title, and publication format, for a reader to be able to access the original source.
The ability to interpret citations is a fundamental research skill!
"Why Cite Information Sources?." How To Do Research. KYVL, 2 July 2004. Web. 5 Aug. 2014. <http://legacy.kyvl.org/html/tutorial/research/citesource.shtml>.