Columbia subject headings:
Abbasids.
Islamic Empire--Historiography.
Harvard subject headings:
Abbasids.
Iraq--History--634-1534--Historiography.
Islamic Empire--Historiography.
Islamic Empire--History--661-750--Historiography.
Islamic Empire--History--750-1258--Historiography.
Princeton subject headings:
Islamic Empire--History--661-750--Historiography.
Islamic Empire--History--750-1258--Historiography.