Columbia subject headings:
Harvard subject headings:
Political purges--Soviet Union--History.
Secret service--Soviet Union--History
Soviet Union--Politics and government--1936-1953.
Soviet Union. Narodnyĭ komissariat vnutrennikh del--History.
Princeton subject headings:
Political purges--Soviet Union--History.
Secret service--Soviet Union--History.
Soviet Union--Politics and government--1936-1953.
Soviet Union. Narodnyĭ komissariat vnutrennikh del--History.