Number | Name | Date | Kind |
---|---|---|---|
3554302 | Adkins | Jan 1971 | |
3595326 | Claycomb | Jul 1971 |
Entry |
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"Rotary Drilling Holes in Coal Beds for Degasification," Bureau of Mines Report of Investigation 8097, U.S. Department of the Interior, 1975, Joseph Cervik et al. |