I’d heard some negative things about today’s book before I picked up a copy, and I was happily surprised by its usefulness. The book is German Pistols and Holsters 1934/1945, by Major Robert D. Whittington III. It is a pretty straight-forward work, written to aid collectors and historians in understanding and identifying the handguns that were used by German military, police, and Nazi party officials. Each of those groups used a different procurement process and different associated markings. The military ones are pretty well documented, but it is much rarer to find a useful discussion of police- and party-specific weapons.
The mainstays of the German sidearm at this time were the P08 Luger and the Walther P38, but a wide variety of foreign-made pistols were also used, from Belgian High Powers to Polish vis 35 Radoms to French Uniques. Whittington covers all of these, explaining what specific markings should or could appear on each, when they were procured, and how many were used. It is not a particularly flowery book, but I found it quite useful. The numerical data is well presented, and the descriptive notes about each gun are both concise and pleasantly informative themselves.
Original copies of German Pistols and Holsters are pretty spendy, but the recent reprint has all the information at a quite reasonable price: