https://sarabander.github.io/sicp/html/index.xhtml#SEC_Conte...
And also this:
EPUB - https://github.com/sarabander/sicp-epub/blob/master/sicp.epu...
PDF - https://github.com/sarabander/sicp-pdf/raw/master/sicp.pdf
https://lockywolf.wordpress.com/2021/02/08/solving-sicp/
The math stuff is brutal.
I suppose it is something to do with the fact that it has been, what, almost 40 years since the lectures?
The fact that most of the code would still work is a miracle. That wouldn't work for, say, Java (which didn't exist in 1986). Nor C++. Nor Javascript (also not there back then). Fortran and C might be able to pull it off (but barely).
Remember, we didn't have computers worth the name back then. Shoot, we didn't even have dirt yet, just rocks.