Columbia subject headings:
Harvard subject headings:
Great Britain. Special Operations Executive
Great Britain. Special Operations Executive--History.
World War, 1939-1945--Secret service--Great Britain.
World War, 1939-1945--Underground movements.
Princeton subject headings:
Great Britain--History.
World War, 1939-1945--Secret service--Great Britain.
World War, 1939-1945--Underground movements.