Under CC-SA nonetheless. In fact, Hal Abelson (one of the authors of SICP) was also one of the founders of Creative Commons. Moreover the other author (Gerald J. Sussman) is in the board of directors of the FSF.
FYI, there's a "gray market" paperback version of the AI text you mention available from Amazon at a very reasonable price--about 10% of the standard US version. This is the textbook for at least one AI-related edX MOOC (Columbia).
Concepts, Techniques, and Models of Computer Programming
And the books in the "The Little Schemer" series.
I would also suggest "Artificial Intelligence: A Modern Approach" but this is not from MIT Press.