Columbia subject headings:
Harvard subject headings:
Coal mine accidents--Virginia--Norton.
Coal mines and mining--Virginia--Norton--Safety measures.
Mine accidents--Virginia--Norton.
Mine explosions--Virginia--Norton.
Mine safety--Virginia--Norton.
Princeton subject headings:
Coal mine accidents--Virginia--Norton.
Coal mines and mining--Virginia--Norton--Safety measures.
Mine accidents--Virginia--Norton.
Mine explosions--Virginia--Norton.
Mine safety--Virginia--Norton.