Columbia subject headings:
Harvard subject headings:
Emperors--Rome--Textbooks.
Rome--History--Empire, 30 B.C.-284 A.D.--Textbooks.
Rome--Politics and government--Empire, 30 B.C.-284 A.D.--Textbooks.
Princeton subject headings:
Rome--Politics and government.--Empire, 30 B.C.-284 A.D..