York: Oxford University Press. ISBN 0-19-509514-6 . http://www.codesandciphers.org.uk/virtualbp/poles/poles.htm http://news.bbc.co.uk/2/hi/europe/8158782.stm Much of the German cipher traffic was encrypted on the Enigma machine, hence the term " Ultra " has often been used almost synonymously with " Enigma decrypts ". However, Ultra also encompassed decrypts of the German Lorenz SZ 40 and 42