Columbia subject headings:
Christian civilization--Congresses.
Christianity--Byzantine Empire--History--Congresses.
Christianity--Europe, Eastern--History--Congresses.
Christianity--Middle East--History--Congresses.
Eastern churches--History--Congresses.
Orthodox Eastern Church--History--Congresses.
Pontificium Institutum Orientalium Studiorum--Anniversaries, etc.
Harvard subject headings:
Christian civilization--Congresses.
Christianity--Byzantine Empire--History--Congresses.
Christianity--Europe, Eastern--History--Congresses.
Christianity--Middle East--Congresses.
Christianity--Middle East--History--Congresses.
Eastern churches--Congresses.
Eastern churches--History--Congresses.
Orthodox Eastern Church--Congresses.
Orthodox Eastern Church--History--Congresses.
Pontificium Institutum Orientalium Studiorum--Anniversaries, etc.
Princeton subject headings:
Christianity--Middle East--Congresses.
Eastern churches--Congresses.
Orthodox Eastern Church--Congresses.