Coal mining in Europe. A study of practices in different coal formations and under various economic and regulatory conditions compared with those in the United States
| Egile nagusia: | |
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| Beste egile batzuk: | |
| Formatua: | Liburua |
| Hizkuntza: | English |
| Argitaratua: |
Washington
U.S. Govt. print. off.
1939.
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| Saila: | U.S. Bureau of mines. Bulletin 414
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| Gaiak: |