45 free and open textbooks from MIT OpenCourseWare

"Here at MIT OpenCourseWare, we publish a lot of course materials. Tens of thousands of lecture notes, assignments, exams and other documents. It’s a huge amount of content in which many gems can hide. Open textbooks, in particular, have tended to get lost in the mix, but we’ve known for some time we have a good trove of them on the site".