Columbia subject headings:
Harvard subject headings:
Byzantine Empire--History--1081-1453.
Byzantine Empire--Relations--Holy Roman Empire.
Holy Roman Empire--Civilization--Byzantine influences.
Holy Roman Empire--History--Hohenstaufen, 1138-1254.
Holy Roman Empire--Relations--Byzantine Empire.
Princeton subject headings:
Byzantine Empire--History--1081-1453.
Byzantine Empire--Relations--Holy Roman Empire.
Holy Roman Empire--Civilization--Byzantine influences.
Holy Roman Empire--History--Hohenstaufen, 1138-1254.
Holy Roman Empire--Relations--Byzantine Empire.