Columbia subject headings:
Crusades.
East and West--History.
Europe--Relations--Islamic Empire.
Islamic Empire--History--750-1258.
Islamic Empire--Relations--Europe.
Latin Orient--History.
Harvard subject headings:
Crusades.
Europe--Foreign relations--Islamic countries.
Islamic countries--Foreign relations--Europe.
Middle Ages.
Princeton subject headings:
Crusades.
East and West--History.
Europe--Relations--Islamic Empire.
Islamic Empire--History--750-1258.
Islamic Empire--Relations--Europe.
Latin Orient--History.