Sources:

• Angela Henning of Einen, Germany
• Professor Henning of Einen, Germany
• Filippo Giunta Leica Screw Mount Cameras - A Systematic Approach
• William White Photomacrography - An Introduction - Focal Press 1987 ISBN 0-240-51189-1
• Theo Kisselbach The LEICA Book
• Willy Hahne Hahne Liste
• James Lager Leica: An Illustrated History. Cameras, Lenses and Accessories
• Gunter Osterloh Leica M Advanced Photo School

Prof.Dr.