Whenever you quote or base your ideas on another person's work, you must document the source you used. Even when you do not quote directly from another work, if reading that source contributed to the ideas presented in your paper, you must give the author(s) proper credit. So, whether you are quoting, paraphrasing, or summarizing someone else's ideas you must cite your source. In other words, a citation should be used when content that did not originate with you is used to support your writing.
Content includes:
For more information on what needs to be cited, check out this summary from Yale University.
For help with Chicago Manual of Style citations, we recommend the Purdue Online Writing Lab. You can find their information on Chicago Style citations here.
Please contact a librarian if you need help with your citations.