Columbia subject headings:
Harvard subject headings:
Abbasids--History.
Caliphs--Biography.
Iraq--History--634-1534.
Islamic Empire--History--750-1258.
Islamic Empire--Kings and rulers--Biography.
Princeton subject headings:
Abbasids--History.
Caliphs--Biography.
Iraq--History--634-1534.
Islamic Empire--History--750-1258.
Islamic Empire--Kings and rulers--Biography.