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Keywords from Image Description:
Mines du Boulonnais Travaux de recherche entre l'extrmit occidentale du Bassin houiller du PasdeCalais et la mer. Mines du Boulonnais fr AlbertCharles Olry Topographie souterraine du bassin houiller du Boulonnais ou bassin d'Hardinghen Imprimerie Nationale Paris Creator Albert Olry PDold Mines du Boulonnais