Columbia subject headings:
Harvard subject headings:
Byzantine Empire--Church history.
Catholic Church--Byzantine rite--History.
Catholic Church--Oriental rites--History.
Eastern churches--History.
Orthodox Eastern Church--History.
Russkai︠a︡ pravoslavnai︠a︡ t︠s︡erkovʹ--History.
Princeton subject headings:
Byzantine Empire--Church history.
Orthodox Eastern Church--History.