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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) |