Columbia subject headings:
Industries--Belgium--Liège--History.
Liège (Belgium)--Economic conditions.
Liège (Belgium)--Population--History.
Harvard subject headings:
Industries--Belgium--Liège--History.
Liège (Belgium)--Economic conditions.
Liège (Belgium)--Population--History.
Princeton subject headings:
Demographic transition--Belgium--Liège (Province).
Industries--Belgium--Liège (Province)--History.
Liège (Belgium : Province)--Population--History.