Columbia subject headings:
Feudalism--Soviet Union--History.
Kievan Rus--History--862-1237.
Social classes--Soviet Union--History.
Harvard subject headings:
Feudalism--Russia--History.
Social classes--Russia--History.
Social structure--Russia--History.
Princeton subject headings:
Feudalism--Soviet Union--History.
Russia--History--862-1237.
Social classes--Soviet Union--History.