Presently there are two main resources that index currently available Open Access (OA) textbooks, OpenStax and the Open Textbook Library.
Rice University's OpenStax produces a number of excellent OA textbooks across many disciplines, focusing on high enrollment
entry level courses offered at community colleges and universities. Notably, these textbooks include Instructor resources
such as test banks, PowerPoint slide presentations, and more.
The Open Textbook Library (hosted by the University of Minnesota) collects together over 600 Open Access textbooks from
across the country, including those produced here in Texas by OpenStax. Notably, this large collection includes reviews
from faculty users. The Open Textbook Library main page includes:
"Open textbooks are textbooks that have been funded, published, and licensed to be freely used, adapted, and distributed.
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 library currently
includes 605 textbooks, with more being added all the time."