Open textbooks are free, online learning materials with Creative Commons licenses. Many of the collections will have links to the same books, but each will have a particular focus, and items you can't find in other collections.
OER repositories contain more than just open textbooks. All content featured within these pages is free but usage rights vary. Materials in these repositories are released under a Creative Commons license while some are in the public domain.
Library E-books can also be used as textbook alternative or supplemental materials to enhance delivery of your course. Chapters or pages within an e-book can be downloaded and linked to directly from Desire2Learn.