Columbia subject headings:
Miners--France--Pas-de-Calais--History--20th century.
Miners--Labor unions--France--Pas-de-Calais--History--20th century.
Mining corporations--France--Pas-de-Calais.
Harvard subject headings:
Miners--France--Labor unions--Pas-de-Calais--History--20th century.
Miners--France--Pas-de-Calais--History--20th century.
Miners--Labor unions--France--Pas-de-Calais--History--20th century.
Mining corporations--France--Pas-de-Calais.
Princeton subject headings: