Columbia subject headings:
Communism--Soviet Union--History.
Russia--History--20th century.
Soviet Union--History--Revolution, 1917-1921.
Harvard subject headings:
Communism--Russia--History.
Communism--Soviet Union--History
Russia (Federation)--History--20th century.
Soviet Union--History--Revolution, 1917-1921.
Princeton subject headings:
Communism--Russia--History.
Communism--Soviet Union--History.
Russia--History--20th century.
Soviet Union--History--Revolution, 1917-1921.