Use these quite a bit in my search for info on mostly pre-WW2 shotguns and rifles. My usual go-to four consist of Buxton's Guide to Foreign Firearms, the 1939 Edition of the Shooters Bible, The 15 Year Treasury Edition of the Gun Digest (the Baron's proof-mark info) and the Stoegers First Treasury Edition. Would apreciate learning of any others which are felt of particular usefulness.

All help appreciated.