Columbia subject headings:
Coal mines and mining--West (U.S.)--Congresses.
Coal--West (U.S.)--Congresses.
Harvard subject headings:
Coal mines and mining--West (U.S.)--Congresses.
Coal reserves--West (U.S.)--Congresses.
Coal--West (U.S.)--Congresses.
Princeton subject headings:
Coal mines and mining--West (U.S.)--Congresses.
Coal--West (U.S.)--Congresses.