Columbia subject headings:
Espionage, East German--Germany (West)--History.
Spies--Germany (East)--History.
Harvard subject headings:
Espionage, East German--Germany.
Germany (East). Ministerium für Staatssicherheit.
Spies--Germany.
Princeton subject headings:
Espionage, East German--Germany (West)--History.
Spies--Germany (East)--History.