Columbia subject headings:
Building stones--Conservation and restoration--Congresses.
Stone--Cleaning--Congresses.
Stone--Conservation and restoration--Congresses.
Harvard subject headings:
Architecture--Scotland--Conservation and restoration--Congresses.
Building stones--Conservation and restoration--Congresses.
Building, Stone--Conservation and restoration--Congresses.
Sandstone buildings--Conservation and restoration--Congresses.
Princeton subject headings:
Building stones--Cleaning--Congresses.
Building stones--Deterioration--Congresses.
Building stones--Preservation--Congresses.
Stone buildings--Conservation and restoration--Congresses.