Stemmer, Josef. Die Entwicklung des Raketenantriebes in allgemein verstandlicher Darstellung (A Non-Technical Treatment of the Development of Rocket Propulsion). Zurich, E.A. Hoffman, 1944-1945. Three volumes, wrps, small 4 x 6.25", all three volumes are in excellent condition. Vol I: Raketenfahrt - Raketenflug (Rocket Ride - Rocket Flight). 80pp, photo illus. Rocket principles, rocket cars and trains, early rocket experiments. Hoffman Bibliotek nummer 106. Vol II: Die Raketenwaffen des zweiten Weltkrieges (The Rocket Weapon of WWII). 72pp, photo illus. Rocket weapons, jet aircraft, the V-1, rocket planes, even the US Aircomet. Surprisingly little to nothing on German rocket planes. Hoffman Bibliotek nummer 107. Vol III: Raketenflugprojekte (Rocket Flight Projects). 216pp, illus with photos and drawings. Rocket engines, Oberth, science fiction, even a flying saucer. Hoffman Bibliotek nummer 108. Stemmer was a Swiss Engineer who experimented with liquid fuel rocket engines in the 1930s and was later organizer of the International Astronautical Society.