Kapera, Z. J. (2002). Before Ultra there was Gale: Some contributions to the history of the Polish Enigma, 1932 - 1942. The Enigma Press.
Chicago-Zitierstil (17. Ausg.)Kapera, Zdzisław Jan. Before Ultra There Was Gale: Some Contributions to the History of the Polish Enigma, 1932 - 1942. Kraków [u.a.]: The Enigma Press, 2002.
MLA-Zitierstil (9. Ausg.)Kapera, Zdzisław Jan. Before Ultra There Was Gale: Some Contributions to the History of the Polish Enigma, 1932 - 1942. The Enigma Press, 2002.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.