Columbia subject headings:
Harvard subject headings:
Europe--Relations--Poland--Congresses.
Piast dynasty--Congresses.
Poland--Foreign relations--To 1572--Congresses.
Poland--History--Piast period, 960-1386--Congresses.
Poland--Relations--Europe--Congresses.
Princeton subject headings:
Europe--Relations--Poland.
Piast dynasty.
Poland--Church history--To 1500.
Poland--Commerce--History.
Poland--History--Piast period, 960-1386.
Poland--Relations--Europe.