 |
| |||
| pillar-and-double-stall; pillar-and-stall method; pillar-and-stall; post-and-stall method; post-and-stall | |||
| pillar-and-stall system; post-and-stall system | |||
| система парных штреков: 3 phrases in 1 subject |
| Mining | 3 |
|
| |||
| pillar-and-double-stall; pillar-and-stall method; pillar-and-stall; post-and-stall method; post-and-stall | |||
| pillar-and-stall system; post-and-stall system | |||
| система парных штреков: 3 phrases in 1 subject |
| Mining | 3 |