Ebooks and other library materials are discoverable in your library catalog and potentially usable in your classroom as an alternative to a traditional textbook. Even more options exist, such as content found on the open web, which might be subject to traditional copyright (i.e., not Creative Commons licensed). This page will identify options to make these non-open resources available to your students.
Using library materials and other non-open resources as course materials might be complicated to navigate, but can be made simple if you rely on a few best practices:

American University Library (2010). What Faculty Need to Know About Copyright for Teaching.
Benson, Sara (2017).
California State University, Chico (2019). Using Copyrighted Works in the Classroom.
Manchester University (2019). Copyright for Faculty.