| Author: | Spencer, John D. | 
|---|---|
| Year: | 1970 | 
| Document Type: | USBI | 
| Issuing Agency: | U.S. Dept. of the Interior, Bureau of Mines, | 
| SUDOC: | I 28.27:8479 | 
| Series: | Information circular / United States. Bureau of Mines ; | 
| Report Number: | 8479 | 
| Subjects: | Coal mines and mining | 
| Coal--Research | |
| Coal preparation | |
| Link: | https://hdl.handle.net/2027/mdp.39015078514745 |