Columbia subject headings:
Harvard subject headings:
GULag NKVD--History.
Internment camps--Soviet Union--History
Karlag (Concentration camp)--History.
Sibirskiĭ ITL--History.
Princeton subject headings:
Internment camps--Soviet Union.
Political persecution--Soviet Union.
Political prisoners--Soviet Union.
Soviet Union--Politics and government--1936-1953.
Soviet Union--Politics and government--1953-1985.