Google Docs Versions
In 2020, OpenStax converted the editable versions for some of their books to Google Documents. These files are restricted to instructors who must create an instructor/educator account with OpenStax in order to gain access. Once this account has been approved, verified instructors must go to the Instructor resources section of the targeted book where they may request access to the document by section through its Customization Form.
Note: Not all OpenStax books include an editable version. OpenStax editorial team selects which resources to develop based on the needs and demands of a wide range of educators using their textbooks.
Another possible option would be to see if other people have created a Pressbooks version of an OpenStax book and then clone that version into your own Pressbooks instance. Moving an OpenStax book into Pressbooks is usually a manual process, so there are not many of them.
You can search for these books using the Pressbooks Directory, which allows you to search all Pressbooks networks at once. Try searching “OpenStax.”
Keep in mind that may of these books will be revised/adapted versions of the original OpenStax text.
While OpenStax textbook content is openly licensed, the OpenStax and OpenStax CNX names, logos, and book covers are not and may not be reproduced without the prior and express written consent of Rice University.