Columbia subject headings:
Harvard subject headings:
Espionage, German--United States--History--20th century.
Felfe, Heinz, 1918---Travel--United States.
Germany (West). Bundesnachrichtendienst--History.
Intelligence service--Soviet Union--History.
Secret service--Soviet Union--History
Soviet Union. Komitet gosudarstvennoĭ bezopasnosti--History.
Spies--Germany (West)--Biography.
Spies--Soviet Union--Biography.
Spies--Travel--United States.
United States. Central Intelligence Agency--History.
Princeton subject headings:
Espionage, German--United States--History--20th century.
Felfe, Heinz, 1918---Travel--United States.
Germany (West). Bundesnachrichtendienst--History.
Intelligence service--Soviet Union--History.
Secret service--Soviet Union--History.
Soviet Union. Komitet gosudarstvennoĭ bezopasnosti--History.
Spies--Germany (West)--Biography.
Spies--Soviet Union--Biography.
Spies--Travel--United States.
United States. Central Intelligence Agency--History.