Columbia subject headings:
Espionage--Great Britain--History--20th century.
Espionage--History--20th century.
Hollis, Roger, Sir, 1905-1973.
Intelligence service--Great Britain--History.
Harvard subject headings:
Espionage--Great Britain--History--20th century.
Great Britain. MI5--History.
Hollis, Roger, Sir.
Intelligence officers--Great Britain--Biography.
Princeton subject headings:
Espionage--Great Britain--History--20th century.
Great Britain. MI5--History.
Hollis, Roger, Sir
Intelligence officers--Great Britain--Biography.