Columbia subject headings:
Cathedrals--Conservation and restoration--Congresses.
Cathedrals--Design and construction--History--Congresses.
Harvard subject headings:
Cathedrals--Conservation and restoration.
Cathedrals--Design and construction--History.
Princeton subject headings:
Cathedrals--Conservation and restoration--Congresses.
Cathedrals--Design and construction--History--Congresses.