Columbia subject headings:
Harvard subject headings:
Eavesdropping--Germany (East)--History.
Germany (East). Ministerium für Staatssicherheit--History.
Opposition (Political science)--Germany (East)--History.
Telecommunication--Law and legislation--Germany (East)--History.
Wiretapping--Germany (East)--History.
Princeton subject headings:
Eavesdropping--Germany (East).
Germany (East). Ministerium für Staatssicherheit
Opposition (Political science)--Germany (East)
Telecommunication--Law and legislation--Germany (East).
Wiretapping--Germany (East)--History--Sources.
Wiretapping--Germany (East).