| Number | Date | Country | Kind |
|---|---|---|---|
| PQ4720 | Dec 1999 | AU | |
| PQ8062 | Jun 2000 | AU |
| Number | Name | Date | Kind |
|---|---|---|---|
| 2859953 | Joy | Nov 1958 | A |
| 4118072 | Kelley et al. | Oct 1978 | A |
| 4378132 | Spies et al. | Mar 1983 | A |
| 5129502 | Justice | Jul 1992 | A |
| Number | Date | Country |
|---|---|---|
| 0724736 | Mar 1980 | SU |
| Entry |
|---|
| Hartman, H. (Senior Ed.), SME Mining Engineering Handbook, 1992, 2nd Edition, pp1559,1560,1696. |