Columbia subject headings:
Emperors--Succession--Rome.
Rome--History--Empire, 30 B.C.-284 A.D.
Harvard subject headings:
Emperors--Succession--Rome
Rome--History--Empire, 30 B.C.-284 A.D.
Princeton subject headings:
Emperors--Succession--Rome.
Rome--History--Empire, 30 B.C.-284 A.D.