Via Hacker News: free technical books from before 1964:
Technical books online tubebooks.org
I’ve found that most of the technical books published before about 1964 never had their copyrights renewed, so now are in the public domain. So I am endeavoring to digitize and post some selected books relating to the “vacuum tube age” of electronics here.
Very nicely done. Also interesting: how he does it (bottom of the same page) and other things he’s into.