Number | Name | Date | Kind |
---|---|---|---|
2516421 | Robertson | Jul 1950 | |
4062412 | McIlvanie | Dec 1977 | |
4658916 | Bond | Apr 1987 | |
5195588 | Dave | Mar 1993 |
Number | Date | Country |
---|---|---|
1615353 | Dec 1990 | SUX |
Entry |
---|
"Longer-Than-Seam-Height Drill Development Program", Derby et al, United States Department of the Interior Bureau of Mines, 1978. |