Columbia subject headings:
Basilica di San Petronio (Bologna, Italy)
Church doorways--Italy--Bologna.
Relief (Sculpture)--Conservation and restoration--Italy--Bologna.
Harvard subject headings:
Basilica di San Petronio (Bologna, Italy)
Church doorways--Italy--Bologna.
Relief (Sculpture)--Conservation and restoration--Italy--Bologna.
Princeton subject headings:
Basilica di San Petronio (Bologna, Italy)
Church doorways--Italy--Bologna.
Relief (Sculpture)--Conservation and restoration--Italy--Bologna.