Columbia subject headings:
Harvard subject headings:
Espionage--Germany (East)--History.
Germany (East)--Politics and government
Germany. Bundesnachrichtendienst
Secret service--Germany (East)--History
Princeton subject headings:
Espionage--Germany (East)--History.
Germany (East)--Politics and government.
Germany. Bundesnachrichtendienst
Secret service--Germany (East)--History.