Columbia subject headings:
Civilization, Ancient--Congresses.
Civilization, Medieval--Congresses.
Harvard subject headings:
Byzantine Empire--Civilization--Congresses.
Civilization, Ancient--Congresses
Civilization, Ancient.
Civilization, Medieval--Congresses
Civilization, Medieval.
Europe--History--476-1492.
Europe--History--To 476.
Princeton subject headings:
Civilization, Medieval.
Middle Ages.