Columbia subject headings:
Communism--History--Sources.
Communism--Soviet Union--History--Sources.
Communist International--History--Sources.
Soviet Union--Politics and government--1917-1936--Sources.
Harvard subject headings:
Communist International--History--Sources.
Permanent revolution theory.
Princeton subject headings:
Communism--History--20th century--Sources.
Communism--Soviet Union--History--Sources.
Communist International--History--Sources.
Soviet Union--Politics and government--1917-1936--Sources.