Armand van Ishoven, Meserschmitt, Gentry Books 1975
The M20 was a single engine passenger or cargo plane designed and built in 1928. Though the prototype crashed on its maiden flight, the plane entered service the next year. They were used by Luft Hansa till 1937. Due to Messerschmitt's almost fanatical attention to reducing weight and improving aerodynamics, the M20 could carry 90% of its empty weight in cargo. 15 were built, none remain.