Columbia subject headings:
Byzantine Empire--History--527-1081.
Byzantine Empire--Relations--Holy Roman Empire.
Holy Roman Empire--History--To 1517.
Holy Roman Empire--Relations--Byzantine Empire.
Harvard subject headings:
Byzantine Empire--History--527-1081.
Byzantine Empire--Relations--Holy Roman Empire.
Holy Roman Empire--History--To 1517.
Holy Roman Empire--Relations--Byzantine Empire.
Princeton subject headings:
Byzantine Empire--History.
Europe--Kings and rulers.