Columbia subject headings:
Europe, Northern--Social conditions.
France--Economic conditions--19th century.
France--Economic conditions--20th century.
France--Social conditions--19th century.
France--Social conditions--20th century.
Harvard subject headings:
Belgium--Social conditions.
Europe, Northern--Social conditions.
France--Economic conditions--19th century.
France--Economic conditions--20th century.
France--Social conditions--19th century.
France--Social conditions--20th century.
Nord-Pas-de-Calais (France)--Social conditions.
Princeton subject headings:
Nord-Pas-de-Calais (France)--Economic conditions.
Nord-Pas-de-Calais (France)--Social conditions.