Columbia subject headings:
East European letters--History and criticism--Congresses.
Europe, Eastern--History--Sources--Congresses.
Harvard subject headings:
East European letters--History and criticism--Congresses.
Europe, Eastern--History--Sources--Congresses.
Princeton subject headings:
Exchange of publications--Europe, Central--History.
Exchange of publications--Europe, Eastern--History.
Letter writing--Europe, Central--History.
Letter writing--Europe, Eastern--History.