Columbia subject headings:
Harvard subject headings:
Italy--Church history--476-1400--Congresses.
Italy--History--476-1268--Congresses.
Papacy--History--Congresses.
Princeton subject headings:
Catholic Church--Italy--History--Congresses.
Italy--Church history--476-1400--Congresses.
Papacy--History--To 1500--Congresses.
Regesta pontificum Romanorum. Italia pontificia--Congresses.