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room and pillar mining (угля) | |||
board-and-pillar mining; pillar method | |||
bord-and-pillar mining; room and pillar mining; room-and-pillar mining |
камерно-столбовая разработка: 58 a las frases, 5 temas |
Geología | 1 |
Minería | 48 |
Minería de oro | 2 |
Petróleo y gas | 1 |
Tecnología | 6 |