Columbia subject headings:
Harvard subject headings:
Baltic States--History--Congresses.
Baltic States--Relations--Europe--Congresses.
Europe--History--1492-1648--Encyclopedias.
Europe--Relations--Baltic States--Congresses.
Princeton subject headings:
Baltic States--History--Congresses.
Baltic States--Relations--Europe--Congresses.
Europe--Relations--Baltic States--Congresses.