Based on: WOOD, A. (2001). Structure and Interpretation of Computer Programs, 2nd Ed by Abelson and Sussman, with Sussman, MIT Press, 1996, ISBN 0-262-51087-1, 657pp. Journal of Functional Programming, 11(2), 253–262. doi:10.1017/s0956796801223983:

"The new material on concurrency is rather a disappointment since such a large and fundamental topic is relegated to little more than a convenient link item between lists and streams.

...

The major omission, and it is major, is that types are never fully, or even adequately discussed."

There's more.