Columbia subject headings:
Harvard subject headings:
Germany. Luftwaffe--History--World War, 1939-1945--Sources.
United States. Army Air Forces--History--World War, 1939-1945--Sources.
World War, 1939-1945--Aerial operations, American.
World War, 1939-1945--Aerial operations, German.
World War, 1939-1945--Cryptography.
World War, 1939-1945--Secret service--Great Britain.
Princeton subject headings:
United States. Army Air Forces--History.
World War, 1939-1945--Aerial operations, American.
World War, 1939-1945--Aerial operations, German.
World War, 1939-1945--Cryptography.