Columbia subject headings:
Europe, Eastern--History--Congresses.
Soviet Union--History--Congresses.
Harvard subject headings:
Civilization, Slavic--Congresses.
Europe, Eastern--History--Congresses.
Minorities--Slavic countries--Congresses.
Slavic countries--History--Congresses.
Soviet Union--History--Congresses.
Princeton subject headings:
Europe, Eastern--History--Congresses.
Soviet Union--History--Congresses.