Written by Josef Mötz and Joschi Schuy, “Vom Ursprung der Selbstladepistole” (Origins of the Automatic Pistol) is an absolute gold mine of information on early manually operated and self loading pistols. It is limited to Austro-Hungarian designs and is available only in German, but even so it remains an indispensable resource. From the recognized names like Mannlicher, Frommer, Bergmann or Pieper to the unknown like Vanyek, Beliczay, Kulhanek, or Warnant, this 850+ page tome is chock full of history, photos, and patent information.
There is really no need for me to go into more detail. If you are interested in early handguns, just buy a copy. You will not regret it.