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
| Prif Awdur: | |
|---|---|
| Awduron Eraill: | |
| Fformat: | Llyfr |
| Iaith: | English |
| Cyhoeddwyd: |
Washington
U.S. Govt. print. off.
1939.
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| Cyfres: | U.S. Bureau of mines. Bulletin 414
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| Pynciau: |