| Number | Name | Date | Kind |
|---|---|---|---|
| 2848931 | Troidl | Aug 1958 | |
| 2880657 | Bartlett | Apr 1959 | |
| 3563486 | Mortsel et al. | Feb 1971 | |
| 3640204 | Gordon | Feb 1972 | |
| 3667361 | Meggs et al. | Jun 1972 | |
| 3680462 | Cronig | Aug 1972 | |
| 4167318 | Wareham | Sep 1979 | |
| 4200383 | Bendoni et al. | Apr 1980 |
| Entry |
|---|
| Research Disclosure Apr., 1980 pp. 132-134. |