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| disclosure of ore deposits (1) |
| preparation of ore deposits (1) |
| technology of conducting preparatory workings (1) |
| the methods of underground mining of ores (1) |
| underground mining of ores (1) |
| disclosure of ore deposits (1) |
| preparation of ore deposits (1) |
| technology of conducting preparatory workings (1) |
| the methods of underground mining of ores (1) |
| underground mining of ores (1) |