Columbia subject headings:
Harvard subject headings:
Byzantine Empire--Foreign relations--1081-1453.
Byzantine Empire--History--Angeli, 1185-1204.
Byzantine Empire--History--Comneni dynasty, 1081-1185.
Byzantine Empire--History.
Crusades--First, 1096-1099
Princeton subject headings:
Byzantine Empire--Foreign relations--1081-1453.
Byzantine Empire--History--Angeli, 1185-1204.
Byzantine Empire--History--Comneni dynasty, 1081-1185.