The ultra secret - Winterbotham, F. W. (Frederick William), 1897- (London : Weidenfeld And Nicolson, 1975)
Includes index
Keywords: Winterbotham, F. W. -- 1897-; World War, 1939-1945 -- Cryptography; World War, 1939-1945 -- Secret service -- Great Britain; World War, 1939-1945 -- Personal narratives, British