Columbia subject headings:
Harvard subject headings:
Celestines--Italy--Romagna--History--Congresses.
Romagna (Italy)--Church history--Congresses.
Princeton subject headings:
Celestines--Italy--Marche--History--Congresses.
Celestines--Italy--Romagna--History--Congresses.
Marche (Italy)--Church history--Congresses.
Romagna (Italy)--Church history--Congresses.