There was a project a while ago to do exactly this (in general, not for Halmos's book specifically. I assume that's the one you mean). I can't find it by Goog

There was a project a while ago to do exactly this (in general, not for Halmos's book specifically. I assume that's the one you mean). I can't find it by Googling, but here's an Internet Archive capture of a Project Gutenberg page that collected books for which this had been done: https://web.archive.org/web/20120502091427/https://www.gutenberg.org/wiki/Mathematics_(Bookshelf) https://web.archive.org/web/20120502091427/https://www.guten... .