| |||
| pillaring; square work; stoop system; chute and pillar; system | |||
|
exploitation par piliers : 17 phrases in 4 subjects |
| Coal | 2 |
| Construction | 1 |
| Metallurgy | 13 |
| Natural resourses and wildlife conservation | 1 |
| |||
| pillaring; square work; stoop system; chute and pillar; system | |||
|
exploitation par piliers : 17 phrases in 4 subjects |
| Coal | 2 |
| Construction | 1 |
| Metallurgy | 13 |
| Natural resourses and wildlife conservation | 1 |