Top secret Ultra
By: Peter Calvocoressi.
Publisher: Cassell; Orion Publishing Group, Limited
Published: 1980
Place of publication: London
Language: eng
Number of pages: 132
Subjects: Calvocoressi, Peter.; World War, 1939-1945 -- Cryptography.; World War, 1939-1945 -- Great Britain -- Secret service.
Other titles: Ultra.
Notes: Includes index.