Chicago Manual of Style (Z253.U69 2017 - Online, at the Ref Desk, in Reference, PARC Reference, and in the stacks)
NOTE: There are two versions outlined in Chicago: A, the humanities style, and B, author-date, preferred by social science and science disciplines.
MLA Handbook for Writers of Research Papers (LB2369.G53 2016 - at the Ref Desk, in Reference, and in the stacks)
Publication Manual of the American Psychological Association (BF76.7 .P83 2020 - at the Ref Desk, in Reference, PARC Reference, and in the stacks)
Academic writing requires that you acknowledge use of the intellectual work of others. These are some of the most common situations that require that you identify and give credit to the work of others:
It is not necessary to give credit for commonly known facts or expressions. 
The most recent edition of Turabian’s A Manual for Writers of Research Papers, Theses, and Dissertations gives four reasons for citing outside sources used in your writing:
• To give credit
• To assure readers of the accuracy of your facts
• To show readers the research tradition that informs your work
• To help readers follow or extend your research 
Failure to give credit to the ideas of others, whether intentional or not, constitutes plagiarism and is a violation of Reed’s Honor Principle as described in the Reed College Guidebook:
"Academic misconduct is a breach of the principle of proper academic conduct and includes both intentional acts of misrepresenting another's work as one's own as well as unintentional acts that fail to conform to the rules of appropriate attribution and credit. Academic misconduct is a violation of Reed's Honor Principle in its most fundamental form and is contrary to the idea of scholarship."
 Kate L. Turabian, A Manual for Writers of Research Papers, Theses, and Dissertations: Chicago Style for Students and Researchers, 7th ed., revised by Wayne C. Booth et al. (Chicago: University of Chicago Press, 2007), 133-34.