Columbia subject headings:
Harvard subject headings:
Coal mines and mining--France--Nord-Pas-de-Calais.
Nord-Pas-de-Calais (France)--Economic conditions.
Nord-Pas-de-Calais (France)--History.
Nord-Pas-de-Calais (France)--Social life and customs.
Princeton subject headings:
Coal mines--France--Nord-Pas-de-Calais.
Nord-Pas-de-Calais (France)--Economic conditions.
Nord-Pas-de-Calais (France)--History.
Nord-Pas-de-Calais (France)--Social life and customs.