Columbia subject headings:
Rome--Civilization--Congresses.
Rome--History--Empire, 30 B.C.-284 A.D.--Congresses.
Harvard subject headings:
Rome--History--Period of military anarchy, 235-284--Congresses.
Rome--History--Severans, 193-235--Congresses.
Princeton subject headings:
Rome--Civilization--Congresses.
Rome--History--Empire, 30-284--Congresses.