Columbia subject headings:
Cossacks--History--20th century.
Soviet Union--History--Revolution, 1917-1921--Cossacks.
Harvard subject headings:
Cossacks--History--20th century.
Soviet Union--History--Revolution, 1917-1921--Participation, Cossack.
Princeton subject headings:
Cossacks--History--20th century.
Soviet Union--History--Revolution, 1917-1921--Cossacks.