| Number | Name | Date | Kind |
|---|---|---|---|
| 3192307 | Lazar | Jun 1965 | |
| 3700788 | Spurck | Oct 1972 | |
| 3826984 | Epple | Jul 1974 | |
| 3991463 | Squitieri et al. | Nov 1976 | |
| 4255003 | Berg | Mar 1981 |
| Number | Date | Country |
|---|---|---|
| 2056193 | Aug 1971 | DEX |
| Entry |
|---|
| Sid International Symposium Digest of Technical Papers, Chicago, IL, L. S. Buchoff, pp. 64, 65; 5-1979. |