* James Gannon, "Stealing Secrets, Telling Lies: How Spies and Codebreakers Helped Shape the Twentieth Century", Washington, D.C., Brassey's, 2001, ISBN 1-57488-367-4.
* James Gannon, "Stealing Secrets, Telling Lies: How Spies and Codebreakers Helped Shape the Twentieth Century", Washington, D.C., Brassey's, 2001, ISBN 1-57488-367-4.