The "Pressbooks Directory" is now included in OERSI: https://oersi.org/resources?provider=%5B%22Pressbooks+Directory%22%5D

It includes textbooks from quite a few Pressbooks instances. It's easy to copy, revise, remix, and redistribute any openly licensed content found here using Pressbooks' publishing platform.

This means that about 5900 more textbooks from a wide range of disciplines can be found in OERSI, and the total number of resources to be found in OERSI has increased from about 70k to about 76k.

see https://pressbooks.directory #oer