 |
| |||
| 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 |