Instructors are the final authority on how they would like you to cite your work. Librarians will refer to the established handbooks when necessary to determine how to cite a particular resource.
MLA Handbook (9th ed.)
MLA Handbook (8th ed.)
Publication Manual of the American Psychological Association: The Official Guide to APA Style (7th ed.)
The Chicago Manual of Style
A Manual for Writers of Research Papers, Theses, and Dissertations by