Columbia subject headings:
Industries--Germany--Ruhr (Region)
Industries--Great Lakes Region (North America)
Industries--Wales, South.
Iron industry and trade--Case studies.
Steel industry and trade--Case studies.
Unemployment--Case studies.
Harvard subject headings:
Industries--Germany--Ruhr (Region)
Industries--Great Lakes Region.
Industries--Wales, South.
Iron industry and trade--Case studies.
Steel industry and trade--Case studies.
Unemployment--Case studies.
Princeton subject headings:
Industries--Germany--Ruhr (Region)
Industries--Great Lakes Region.
Industries--Wales, South.
Iron industry and trade--Case studies.
Steel industry and trade--Case studies.
Unemployment--Case studies.