Columbia subject headings:
Baltic Sea Region--History--Congresses.
Baltic Sea Region--History--To 1500--Congresses.
Baltic States--History--Congresses.
Christianity--Baltic Sea Region--History--Congresses.
Christianity--Baltic States--History--Congresses.
Church history--Middle Ages, 600-1500--Congresses.
Crusades--Baltic Sea Region--History--Congresses.
Crusades--Congresses.
Harvard subject headings:
Baltic States--History.
Crusades
Princeton subject headings:
Baltic Sea Region--History.
Baltic States--History.
Christianity--Baltic Sea Region--History.
Christianity--Baltic States--History.
Church history--Middle Ages, 600-1500.
Crusades.