Columbia subject headings:
Harvard subject headings:
Balkan Peninsula--History.
Bulgaria--History--To 1393.
Byzantine Empire--Civilization.
Byzantine Empire--History.
Civilization, Slavic--Byzantine influences.
Slavic philology.
Princeton subject headings:
Bulgaria--History--To 1393.
Byzantine Empire--Civilization.
Civilization, Slavic--Byzantine influences.
Slavic philology.