Władysław Kozaczuk, Enigma: How the German Machine Cipher Was Broken, and How It Was Read by the Allies in World War Two, edited and translated by Christopher Kasparek, Frederick, MD, University Publications of America, 1984, ISBN 0-89093-547-5.
:Ludomir Danilewicz - Polish engineer, one of the directors of AVA together with Leonard Danilewicz, helped to break the Enigma Code