Columbia subject headings:
Byzantine Empire--Foreign relations--1081-1453.
Crusades--Influence.
Islam--Relations--Christianity.
Turkey--History--1288-1453.
Harvard subject headings:
Byzantine Empire--Foreign relations--1081-1453.
Byzantine Empire--Foreign relations--Europe.
Byzantine Empire--Foreign relations--Islamic Empire.
Crusades--Influence.
Europe--Foreign relations--Byzantine Empire.
Islam--Relations--Christianity
Islamic Empire--Foreign relations--Byzantine Empire.
Turkey--History--1288-1453.
Princeton subject headings:
Byzantine Empire--Foreign relations--1081-1453.
Crusades--Influence.
Islam--Relations--Christianity.
Turkey--History--1288-1453.