Columbia subject headings:
Harvard subject headings:
Europe--History--Philosophy--Congresses.
History--Philosophy--Congresses
History--Philosophy--History--19th century--Congresses.
History--Philosophy--History--20th century--Congresses.
Poland--History--Philosophy--Congresses.
Russia--History--Philosophy--Congresses.
Princeton subject headings:
Europe--History--Philosophy--Congresses.
History--Philosophy--Congresses.
Russia--History--Philosophy--Congresses.