Columbia subject headings:
Harvard subject headings:
Church and state--Rome--Early works to 1800.
Church history--Primitive and early church, ca. 30-600
Emperors--Rome--Early works to 1800
Persecution--History--Early church, ca. 30-600
Rome--History--Empire, 30 B.C.-476 A.D.
Princeton subject headings:
Church and state (Roman law)
Church history.