Columbia subject headings:
Calvocoressi, Peter.
World War, 1939-1945--Cryptography.
World War, 1939-1945--Personal narratives, British.
World War, 1939-1945--Secret service--Great Britain.
Harvard subject headings:
Calvocoressi, Peter.
World War, 1939-1945--Cryptography.
World War, 1939-1945--Personal narratives, British.
World War, 1939-1945--Personal narratives, English.
World War, 1939-1945--Secret service--Great Britain.
Princeton subject headings:
World War, 1939-1945--Cryptography.
World War, 1939-1945--Personal narratives, British.
World War, 1939-1945--Secret service--Great Britain.