Columbia subject headings:
Church history--Primitive and early church, ca. 30-600.
Clergy--History.
Emigration and immigration--Religious aspects--Christianity--History.
Harvard subject headings:
Church history--Primitive and early church, ca. 30-600--Congresses.
Clergy--History--Congresses.
Emigration and immigration--Religious aspects--Christianity--History--Congresses.
Europe--History--392-814--Congresses.
Princeton subject headings:
Church history--Primitive and early church, ca. 30-600.
Clergy--History.
Emigration and immigration--Religious aspects--Christianity--History.