Columbia subject headings:
Mine safety--Research--United States--History.
Mining engineering--Research--United States--History.
United States. Bureau of Mines--History.
Harvard subject headings:
Mine safety--Research--United States--History.
Mining engineering--Research--United States--History.
United States. Bureau of Mines--History.
Princeton subject headings:
Mine safety--Research--United States--History.
Mining engineering--Research--United States--History.
United States. Bureau of Mines--History.