Seems like Flat World Knowledge would be a great place for them to start if they're looking for free CC-BY-NC-SA textbooks. http://catalog.flatworldknowledge.c

Seems like Flat World Knowledge would be a great place for them to start if they're looking for free CC-BY-NC-SA textbooks. http://catalog.flatworldknowledge.com/catalog/disciplines http://catalog.flatworldknowledge.com/catalog/disciplines Disclosure: I did a summer internship there, everyone is awesome and I loved it.