Columbia subject headings:
Social classes--Soviet Union--History--20th century.
Socialism--Soviet Union--History--20th century.
Soviet Union--Economic conditions.
Soviet Union--Social conditions.
Harvard subject headings:
Social classes--Soviet Union--History--20th century.
Socialism--Soviet Union--20th century.
Socialism--Soviet Union--History--20th century.
Soviet Union--Economic conditions.
Soviet Union--Social conditions.
Princeton subject headings: