Columbia subject headings:
Islamic Empire--History--Early works to 1800.
Zaydīs--History--Early works to 1800.
Harvard subject headings:
Islamic Empire--History--Early works to 1800.
Zaydīs--History--Early works to 1800.
Princeton subject headings:
Islamic Empire--History--622-661--Early works to 1800.
Zaydīs--History--Early works to 1800.