To document sources means to include within your work the information necessary:
The compact unit of information included to credit each source used in your work is called a citation. When you include a citation for a source of information you used in your work, it can be said that you cited that source.
The University of Wisconsin-Madison Writing Center suggests that you should document:
(Source: "The Writer's Handbook: About Documentation Styles." The Writing Center. Univ. Wisconsin-Madison, 29 Aug. 2014. Web. 21 Oct. 2015.)
A documentation style is a standard method for creating citations used by a particular academic discipline. A documentation style not only provides formats for citing information sources on the final References or Works cited page and within the body of the paper; it also dictates specifics for formatting the body of the paper itself.
A few of the most widely used documentation styles today include those created for:
When you are given a research assignment, the instructor will provide information on which documentation style to use and specific information on how to format citations and other aspects of documentation. See Help for Constructing Citations for more information.
However, keep in mind that as a college student, you are expected to credit any ideas that are not your own in all your work. To fail to cite sources at any time is unethical, and comes with consequences. See Avoiding Plagiarism.