These books have been reviewed by faculty from a variety of colleges and universities to assess their quality. These books can be downloaded for no cost, or printed at low cost. All textbooks are either used at multiple higher education institutions; or affiliated with an institution, scholarly society, or professional organization.
The Open Textbook Library provides a growing catalog of free, peer-reviewed, and openly-licensed textbooks, from a variety of sources. This site also includes reviews from faculty members who have adopted these materials.
Open source textbooks that are written by professional content developers who are experts in their fields and undergo a rigorous peer review process. All textbooks meet standard scope and sequence requirements.