Columbia subject headings:
Harvard subject headings:
Espionage, East German--Germany--History--20th century.
Intelligence service--Germany--History--20th century.
Spies--Germany--Biography.
World War, 1939-1945--Secret service--Germany.
Princeton subject headings:
Espionage, East German--Germany--History--20th century.
Intelligence service--Germany--History--20th century.
Spies--Germany--Biography.
World War, 1939-1945--Secret service--Germany.