You must use citations when:
When in doubt, cite it!
The only people who really love the complexities of accurate citation format are (some) scholars and (some) librarians. For the rest of us, citation generators can help keep track of sources and produce a correctly format bibliography in the appropriate style.
Try this excellent tool:
NoodleTools is a bibliographic citation and notes management tool. It supports you in creating citations for various source types in the appropriate style, and also helps you keep those citations associated with the notes that you take on the sources you use. It is simple to use and will save you time.
When writing this paper, you will be using the MLA format. MLA uses parenthetical references (instead of footnotes). If you have any questions, please see a librarian at the Welcome desk for assistance with using the MLA Handbook.