Echoing Tim, it's a book I'd recommend. Nagel includes pics from his service in the war, and they are equally interesting along with the text. His first battery(BAK 54) was equipped with th 7,7cm :/35 (Frnz.) Later Nagel was transfered to K-Flak 82 and the battery was equipped with Model 1914 Daimler platform trucks carrying the Krupp M1914 7,7cm.