| Number | Date | Country | Kind |
|---|---|---|---|
| 63-112169 | May 1988 | JPX | |
| 63-136717 | Jun 1988 | JPX | |
| 64-10298 | Jan 1989 | JPX | |
| 64-11251 | Jan 1989 | JPX |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3380828 | Kitze et al. | Apr 1968 | |
| 3666457 | Youngquist et al. | May 1972 | |
| 3672891 | Wyand et al. | Jun 1972 | |
| 3672896 | Gabrielsen et al. | Jun 1972 | |
| 4775612 | Abe et al. | Oct 1988 |
| Entry |
|---|
| Research Disclosure, vol. 207, No. 20733 (Jul. 1981). |