Columbia subject headings:
Byzantine Empire--Congresses.
Byzantine Empire--Relations--Europe, Eastern--Congresses.
Europe, Eastern--Relations--Byzantine Empire--Congresses.
Harvard subject headings:
Byzantine Empire--History--Congresses.
Byzantine Empire--Relations--Europe, Central--Congresses.
Byzantine Empire--Relations--Europe, Eastern--Congresses.
Europe, Central--Relations--Byzantine Empire--Congresses.
Europe, Eastern--Relations--Byzantine Empire--Congresses.
Princeton subject headings:
Byzantine Empire--Congresses.
Byzantine Empire--Relations--Europe, Eastern--Congresses.
Europe, Eastern--Relations--Byzantine Empire--Congresses.