Columbia subject headings:
Architectural ironwork--Europe--History--Congresses.
Architecture, Medieval--Congresses.
Building materials--Europe--History--Congresses.
Building, Stone--Europe--History--Congresses.
Leadwork--Europe--History--Congresses.
Harvard subject headings:
Architectural metal-work--Europe--History--Congresses.
Architecture, Medieval--Congresses
Building, Stone--Europe--History--Congresses.
Leadwork--Europe--History--Congresses.
Princeton subject headings:
Architectural ironwork--Europe--History--Congresses.
Architecture, Medieval--Congresses.
Building materials--Europe--History--Congresses.
Building, Stone--Europe--History--Congresses.
Leadwork--Europe--History--Congresses.