MAHON, A.P.. The History of Hut Eight: 1939–1945 [online]. AlanTuring.net, jún 1945, [cit. 2010-09-07]. Dostupné online. ((po anglicky))
cam.ac.uk
cl.cam.ac.uk
SIR HINSLEY, Harry. The Influence of ULTRA in the Second World War [online]. Babbage Lecture Theatre, Computer Laboratory: TMA Lomas and Computer Security Group, Computer Laboratory, University of Cambridge, 19.10.1993, rev. 1996-11-26, [cit. 2010-06-27]. Dostupné online. Archivované 2012-07-06 z originálu. ((po anglicky))
interklasa.pl
matematycy.interklasa.pl
PIETROŃ, Paweł. Rejewski Marcin [online]. Matematycy i nie tylko, ?, rev. 2007-08-14, [cit. 2010-10-07]. Dostupné online. ((po poľsky))
nsa.gov
MINE, A. Ray. The Cryptographic Mathematics of Enigma (.pdf) [online]. National Security Agency. Dostupné online. Archivované 2009-01-17 z originálu. ((po anglicky))
MINE, A. Ray. The Cryptographic Mathematics of Enigma (.pdf) [online]. National Security Agency. Dostupné online. Archivované 2009-01-17 z originálu. ((po anglicky))
SIR HINSLEY, Harry. The Influence of ULTRA in the Second World War [online]. Babbage Lecture Theatre, Computer Laboratory: TMA Lomas and Computer Security Group, Computer Laboratory, University of Cambridge, 19.10.1993, rev. 1996-11-26, [cit. 2010-06-27]. Dostupné online. Archivované 2012-07-06 z originálu. ((po anglicky))