Columbia subject headings:
Cattedrale di Ferrara.
Church doorways--Conservation and restoration--Italy--Ferrara.
Relief (Sculpture)--Conservation and restoration--Italy--Ferrara.
Harvard subject headings:
Cattedrale di Ferrara.
Doorways--Italy--Ferrara--Conservation and restoration.
Relief (Sculpture)--Conservation and restoration--Italy--Ferrara.
Princeton subject headings: