Columbia subject headings:
Russia (Federation)--History.
Russia--History--20th century.
Soviet Union--History.
Harvard subject headings:
Revolutions and socialism--Russia--History--20th century.
Revolutions and socialism--Soviet Union--History.
Russia (Federation)--History--20th century.
Russia (Federation)--History.
Soviet Union--History.
Princeton subject headings:
Russia (Federation)--History.
Russia--History--20th century.
Soviet Union--History.