Links are offered to the site's own content on Lumen's Candela Learning catalog and well as content developed by other institutions it has worked with on OER initiatives. Content is made available in HTML format which can be accessed through a school's LMS.
California State University System manages a catalog of thousands of resources in science and technology, math and statistics, humanities, and education. Resources other than textbooks are offered here.
MIT provides an online textbook page along with links to the textbook files used in their online courses. This site is useful for course materials not covered by other sources.
The nonprofit Institute for the Study of Knowledge Management in Education launched this site to share content from around the world. College level textbooks represent around 600 results and many are listed in other collections in this list.
This site lists a meta collection of free textbooks many taken from other sites listed here. Other collections of free online courses, movies, audio books and other forms of education content are listed.
The University of Minnesota supports this site which represents a consortium of higher education institutions who networked to use OER in their programs. The library of textbooks pulls titles from many sources including some in this list.
Rice University launched this site with 13 titles. There are now 22 in subject areas ranging from anatomy to sociology. The parent organization OpenStax CNX provides an open library of learning objects that can be utilized in custom curricula.
Directed by a chemistry professor at UC Davis, this collaborative project focuses on STEM topics and invites students and professors to develop content and then share it. Items offered: labs, homework and worksheets. Current subjects covered: chemistry, biology, geology, statistics, physics, math and solar.
Wikimedia Foundation hosts this site which offers 2,900 textbooks categorized by subject, completion status and reading level. Many of the books can be downloaded as PDF files.