Columbia subject headings:
Forced labor--Soviet Union.
Political persecution--Soviet Union.
Political prisoners--Soviet Union--Correspondence.
Porshnev, G. I. (Georgiĭ Ivanovich), 1887-1937--Correspondence.
Porshnev, G. I. (Georgiĭ Ivanovich), 1887-1937.
Soviet Union--Politics and government--1917-1936.
Soviet Union--Politics and government--1936-1953.
Harvard subject headings:
Porshnev, Georgii Ivanovich--Correspondence.
Porshneva, G. G.--Correspondence.
Princeton subject headings:
Forced labor--Soviet Union.
Political persecution--Soviet Union.
Political prisoners--Soviet Union--Correspondence.
Porshnev, G. I. (Georgiĭ Ivanovich), 1887-1937--Correspondence.
Porshnev, G. I. (Georgiĭ Ivanovich), 1887-1937.
Soviet Union--Politics and government--1917-1936.
Soviet Union--Politics and government--1936-1953.