Filter by: Subject
Зараз показуються 1-10 з 1
| band pillars coal (1) |
| distance on normaly (1) |
| field preparation (1) |
| skate for lowering of coal (1) |
| steep layers (1) |
| the PMP area (1) |
| venting horizon (1) |
| width of pillar (1) |
| вентиляционный горизонт (1) |
| вентиляційний горизонт (1) |