Interesting! Now I want to read this book.

Thanks man. Started reading GEB last Saturday and I could figure out the "HE" and "HEADACHE" ones but did not realize that "HEADACHE" was also the response to tha "ADAC" puzzle.

Cheers from Argentina,
TKD

Thank you for posting this! Just came here to say that there is a Reddit community at https://www.reddit.com/r/GEB/ that hosts discussion of this book.