Open Textbook Library
The University of Minnesota oversees this library of open textbooks for a network of universities that are working to make openly accessible textbooks available. All textbooks in this library are complete and openly licensed. The site allows users to search for and link to open textbooks in multiple subject areas. Some textbooks are reviewed and starred similar to those on Amazon. URL: https://open.umn.edu/opentextbooks/
OpenStax
OpenStax College, an initiative of Rice University sponsored by a number of foundations, is a nonprofit organization that is working to improve student access to educational resources. The site has a collection of free textbooks that are developed and peer-reviewed by educators. Faculty can request access to supplemental materials. URL: https://cnx.org/
BC Campus OpenEd
The government of British Columbia is working to make education more accessible and affordable by funding development of and providing access to openly accessible textbooks. URL: https://open.bccampus.ca/
MIT OpenCourseWare Textbooks
The MIT OpenCourseWare site includes open textbooks. The texbook site is organized by general subject area. The site includes links to openly licensed electronic versions of print books, self-published online books, and detailed course notes that can serve as an alternatives to conventional textbooks. Online textbooks are linked under the Find Courses pull-down. URL: https://ocw.mit.edu/courses/online-textbooks/
National Academies Press
National Academies Press (NAP) publishes the reports of the Academies. NAP publishes more than 200 books a year on a variety of topics in science, engineering, and medicine. The information is authoritative and discusses important issues in science and health policy. The books are available online for free, although users must register to download content. URL: http://www.nap.edu/
LibreTexts: The Geosciences Library is one of several subject collections with the LibreTexts open textbook environment. LibreTexts is a non-profit organization based at the University of California, Davis and with support from the US Department of Education, NSF, and other agencies. URL: https://geo.libretexts.org
Directory of Open Access Books: DOAB is a discovery service that indexes and provides access to scholarly Open Access books of all kinds (including textbooks) from over 600 publishers.
Open Syllabus Explorer: Search millions of syllabi from colleges and universities in 140 countries, including lists of assigned open textbooks, using Open Syllabus Explorer. URL: https://opensyllabus.org/