Columbia subject headings:
Espionage, British--History--20th century.
Great Britain. MI6--Biography.
Intelligence officers--Great Britain--Biography.
Oldfield, Maurice, Sir, 1915-1981.
Harvard subject headings:
Espionage, British--History--20th century.
Great Britain. MI6--Biography.
Intelligence officers--Great Britain--Biography.
Oldfield, Maurice, Sir, 1915-1981.
Princeton subject headings:
Great Britain. MI6
Oldfield, Maurice, Sir, 1915-1981.
Spies--Great Britain--Biography.