 |
| |||
| board-and-stall working; board-and-stoop mining; room-and-pillar mining | |||
| камерностолбовая выемка: 3 phrases in 1 subject |
| Mining | 3 |
|
| |||
| board-and-stall working; board-and-stoop mining; room-and-pillar mining | |||
| камерностолбовая выемка: 3 phrases in 1 subject |
| Mining | 3 |