Columbia subject headings:
Harvard subject headings:
Cities and towns--Europe, Central--History--Congresses.
Europe, Central--Economic conditions--Congresses.
Europe, Central--Social conditions--Congresses.
Industries--Europe, Central--Social aspects--Congresses.
Princeton subject headings:
Cities and towns--Europe, Central--History--Congresses.
Europe, Central--Economic conditions--Congresses.
Europe, Central--Social conditions--Congresses.
Industries--Social aspects--Europe, Central--Congresses.