Columbia subject headings:
Harvard subject headings:
Iron and steel workers--Germany--History.
Iron and steel workers--United States--History.
Iron industry and trade--Germany--History.
Iron industry and trade--United States--History
Steel industry and trade--Germany--History
Steel industry and trade--United States--History
Princeton subject headings:
Iron and steel workers--Germany--History.
Iron and steel workers--United States--History.
Iron industry and trade--Germany--History.
Iron industry and trade--United States--History.
Steel industry and trade--Germany--History.
Steel industry and trade--United States--History.