The Bergmann-Bayard was one of the more successful early automatic pistols, along with the better-known C96 “Broomhandle” Mauser. Chambered in a potent 9x23mm cartridge, several thousand were sold to the Spanish and Danish governments (in Denmark, it was a standard issue sidearm until 1946).
German (click to download in PDF format)
Photos of a Bergmann-Bayard M1910/21 (click to download high-resolution copies)
For a bit more history on the weapon, I suggest the review by Guns & Ammo magazine.