How can I search for physical library sources- as in, ignoring e-books?
Try searching through WorldCat local. There is a link to it on the library homepage: WorldCat@USD.) Once there enter the keyword or subject and click search. When the results come up you can then limit results to books, journals, etc., by clicking boxes on the left side of the results page.
You can also contact a subject specialist/liaison librarian (http://www.usd.edu/library/specialists) for additional tips and/or to meet with your class.