Columbia subject headings:
Civilization, Medieval--Congresses.
Middle Ages--Congresses.
Middle Ages--Influence--Congresses.
Harvard subject headings:
Civilization, Medieval--Congresses
Middle Ages--Congresses
Middle Ages--Influence--Congresses.
Princeton subject headings:
Civilization, Medieval--Congresses.
Middle Ages--Congresses.
Middle Ages--Influence--Congresses.