Columbia subject headings:
Islamic Empire--History--622-661.
ʻUthmān ibn ʻAffān, Caliph, -656.
Harvard subject headings:
Islamic Empire--History--622-661.
ʻUthmān ibn ʻAffān, Caliph, -656.
Princeton subject headings:
Islamic Empire--History--622-661.
ʻUthmān ibn ʻAffān, Caliph, -656.