BC Campus - BC Campus provides a curated list of open textbooks. In the meantime, the BC government, like California, is funding the creation of Open Textbooks for high enrollment undergraduate courses. It is part of their Open Textbook Project. BC Campus Authoring Guide is at https://opentextbc.ca/opentextbook/
College Open Text Books - "The Community College Open Textbooks Collaborative is funded by The William and Flora Hewlett Foundation. This collection of sixteen educational non-profit and for-profit organizations, affiliated with more than 200 colleges, is focused on driving awareness and adoptions of open textbooks to more than 2000 community and other two-year colleges."
Global Text Project - chapters of the open textbooks are maintained in open document format.
Lumen Learning - "Lumen Learning courseware helps improve educational access, affordability and student success, simultaneously."
MERLOT - MERLOT's collection has over 900 Open Textbooks, and it allows you to search for textbooks by subject, whereas many other sites just provide list of books, which can get unwieldy. Click on a link to your subject area and you then get a hit list of Open Textbooks in different sub-disciplines. Log into Merlot and click on Content Builder to create an open textbook.
NOBA - Psychology open textbooks. Create an account to select or build an open textbook.
OER Commons - "OER Commons is a dynamic digital library and network. Explore open education resources and join our network of educators dedicated to curriculum improvement." Go to https://www.oercommons.org/authoring-overview to log in an use OER Commons Authoring platform.
Open Culture - "The best free cultural & educational media on the web."
OpenStax College - "OpenStax College offers students free textbooks that meet scope and sequence requirements for most courses. These are peer-reviewed texts written by professional content developers." OpenStax is an initiative of Rice University. OpenStax CNX is their authoring platform.
Open Textbook Library - All textbooks in the University of Minnesota catalog must meet four conditions: (1) Openly licensed (2) Complete (3) Suitable for adoption outside the author's institution (4) Available in print.