Hager, Nicky; Secret Power, New Zealand's Role in the International Spy Network; Craig Potton Publishing, Nelson, NZ; ISBN 0-908802-35-8; 1996
Bamford, James; Body of Secrets: Anatomy of the Ultra-Secret National Security Agency , Anchor, ISBN 0385499086; 2002
Keefe, Patrick Radden Chatter: dispatches from the secret world of global eavesdropping; Random House Publishing, New York, NY; ISBN 1-4000-6034-6; 2005
Bamford, James; The Shadow Factory: The Ultra-Secret NSA from 9/11 to the Eavesdropping on America, Doubleday, ISBN 0385521324; 2008