Columbia subject headings:
Islamic Empire--History--622-661.
Islamic Empire--History--661-750.
Islamic Empire--History--750-1258.
Harvard subject headings:
Islamic Empire--History--622-661.
Islamic Empire--History--661-750.
Islamic Empire--History--750-1258.
Princeton subject headings:
Islamic Empire--History--622-661.
Islamic Empire--History--661-750.
Islamic Empire--History--750-1258.