First read Rule 15 carefully and check your citation to make sure you're using the correct edition. Then search for books or other treatises in Melvyl.
Tip for scanned books: Many books—especially older titles that are out of copyright—are available online in specialty research systems like ECCO (Eighteenth Century Collections Online), MoML (Making of Modern Law), and HeinOnline. Search by title and author to find links to these system from Library Search at lib.uci.edu/library.
If your book is:
Ask a law librarian about books that you can't find in a catalog.