Columbia subject headings:
Harvard subject headings:
El Alamein, Battle of, Egypt, 1942
World War, 1939-1945--Cryptography.
World War, 1939-1945--Secret service--Great Britain.
Princeton subject headings:
El Alamein, Battle of, Egypt, 1942.
World War, 1939-1945--Campaigns--Africa, North.
World War, 1939-1945--Cryptography.
World War, 1939-1945--Secret service--Great Britain.