Open Educational Resources are educational materials--such as courses, assignments, syllabi, and textbooks--that are open for anyone to use and, depending on the license, to re-mix, improve, and redistribute.
You can find all types of OERs on the following sites:
The sites listed below collect links to open textbooks from a variety of sources.
The sites below are collections of open textbooks created by open education publishers.
The Directory of Open Access Books (DOAB) contains almost 9000 books and book chapters that are freely available. You can search the DOAB in the BU Library Search, where you'll also be able to find additional e-book collections to which the BU Libraries has access.
Our research guide to e-books includes a page on open e-books, with links to smaller, more specialized databases of open e-books.