Columbia subject headings:
Harvard subject headings:
Cities and towns, Medieval--Congresses
Cities and towns--Germany--History--Congresses.
Germany--History--Hohenstaufen, 1138-1254--Congresses.
Princeton subject headings:
Cities and towns, Medieval--Congresses.
Cities and towns--Germany--History--Congresses.
Germany--History--Hohenstaufen, 1138-1254--Congresses.