Books & CD-ROM
David Kahn: Seizing Enigma
Andrew Hodges: Alan Turing: the Enigma
*Tom Perera: Inside Enigma
*Tom Perera: The Story of the Enigma CD-ROM
*( order from: )
http://www.arrl.org/shop/History-and-Adventure/?page=2
Simulators
Windows/Mac:
http://users.telenet.be/d.rijmenants/en/enigmasim.htm
I-Phone Apps: Mininigma, The Enigma, etc.