Columbia subject headings:
Crimea (Ukraine)--History--Congresses.
Soviet Union--History--Revolution, 1917-1921--Congresses.
Ukraine--History--Revolution, 1917-1921--Congresses.
Harvard subject headings:
Crimea (Ukraine)--History--Congresses.
Soviet Union--History--Revolution, 1917-1921--Congresses.
Ukraine--History--Revolution, 1917-1921--Congresses.
Princeton subject headings: