Information about Soviet Cameras
Please note that the documents written by Oscar Fricke do not include certain low-production FED models, such as FED "Berdsk" and FED "Red Flag". At the time he researched the subject, information about these variations was scarce and unreliable.
The Dzerzhinsky Commune: Birth of the Soviet 35mm Camera Industry by Oscar Fricke
FED Production Numbers (by Oscar Fricke)
FED Variations (by Oscar Fricke)
Zorki Variations (by Oscar Fricke)
GOST/ASA Conversion Table
How to Load a Leica