Columbia subject headings:
Catholic Church--Relations--Orthodox Eastern Church.
Orthodox Eastern Church--Relations--Catholic Church.
Popes--Primacy--History of doctrines--Middle Ages, 600-1500.
Harvard subject headings:
Catholic Church--Relations--Orthodox Eastern Church.
Orthodox Eastern Church--Relations--Catholic Church.
Popes--Primacy--History of doctrines--Middle Ages, 600-1500.
Princeton subject headings:
Catholic Church--Relations--Orthodox Eastern Church.
Orthodox Eastern Church--Relations--Catholic Church.
Papacy--History--To 1309.