Columbia subject headings:
Espionage, Communist--Vatican City--Sources.
Germany (East). Ministerium für Staatssicherheit.
Intelligence service--Communist countries--History--Sources.
Poland. Służba Bezpieczeństwa.
Soviet Union. Komitet gosudarstvennoĭ bezopasnosti.
Harvard subject headings:
Espionage, Communist--Vatican City--History--Sources.
Espionage, Communist--Vatican City--Sources.
Germany (East). Ministerium für Staatssicherheit.
Intelligence service--Communist countries--History--Sources.
Poland. Służba Bezpieczeństwa.
Soviet Union. Komitet gosudarstvennoĭ bezopasnosti.
Princeton subject headings:
Espionage, Communist--Vatican City--Sources.
Germany (East). Ministerium für Staatssicherheit
Intelligence service--Communist countries--History--Sources.
Poland. Służba Bezpieczeństwa
Soviet Union. Komitet gosudarstvennoĭ bezopasnosti