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carboniferous | |||
carboniferous formation; coal-bearing formation; coal-formation; carboniferous period |
carbonifera : 50 phrases in 8 subjects |
Coal | 8 |
Earth sciences | 6 |
Environment | 2 |
General | 3 |
Industry | 1 |
Metallurgy | 27 |
Mining | 1 |
Social science | 2 |