Columbia subject headings:
Harvard subject headings:
Abbasids--Biography.
Caliphs--Biography.
Islamic Empire--History--750-1258.
Mustaʻṣim Billāh, Caliph, approximately 1212-1258
Princeton subject headings:
Abbasids--Biography.
Caliphs--Biography.
Islamic Empire--History--750-1258.
Mustaʻṣim Billāh, Caliph, approximately 1212-1258.