Columbia subject headings:
Abū Bakr, Caliph, -634.
Arabs--History--To 622.
Islamic Empire--History--622-661.
Muḥammad, Prophet, -632.
Harvard subject headings:
Abū Bakr, Caliph, -634.
Arabs--History--To 622
Islamic Empire--History--622-661.
Muḥammad, Prophet, -632
Princeton subject headings: