Columbia subject headings:
Bituminous coal.
Coal trade--United States--History.
United States--Economic conditions.
Harvard subject headings:
Bituminous coal.
Coal trade--United States--History.
New Deal, 1933-1939.
United States--Economic conditions--1918-1945.
Princeton subject headings:
Bituminous coal.
Coal trade--United States--History.
United States--Economic conditions--To 1933.