Columbia subject headings:
Harvard subject headings:
Castles--History--To 1500--Congresses.
Military history, Medieval--Congresses.
Siege warfare--History--Congresses.
Siege warfare--History--To 1500--Congresses.
Sieges--History--To 1500--Congresses.
Princeton subject headings:
Military history, Medieval--Congresses.
Siege warfare--History--Congresses.