Today we have a copy of John Remling's work, a "Collector's Guide to Tokarev Pistols". It's a thin volume, but a good introduction and basic reference to the development of the TT33 Tokarev pistol and the different nations that adopted it.

Unfortunately, it does appear to be out of print, and I was not able to find a reliable source where you could buy a copy. So keep your eyes open at gun shows, because it is a good value for the money when you find it used.