Columbia subject headings:
Steel industry and trade--Pennsylvania--Pittsburgh Region--History.
Steel industry and trade--United States--History.
United States Steel Corporation--History.
Harvard subject headings:
Steel industry and trade--Pennsylvania--Pittsburgh Region--History.
Steel industry and trade--Pittsburgh Region (Pa.)--History.
Steel industry and trade--United States--History
United States Steel Corporation--History.
Princeton subject headings:
Steel industry and trade--Pennsylvania--Pittsburgh Region--History.
Steel industry and trade--United States--History.
United States Steel Corporation--History.