Columbia subject headings:
Caliphate.
Islam and politics.
Islam and state.
Islamic Empire--History.
Islamic Empire--Politics and government.
Harvard subject headings:
Caliphate
Islam and politics.
Islam and state.
Islamic Empire--History.
Islamic Empire--Politics and government.
Princeton subject headings:
Caliphate.
Islam and politics.
Islam and state.
Islamic Empire--History.
Islamic Empire--Politics and government.