| Number | Name | Date | Kind |
|---|---|---|---|
| 2997295 | Beck | Aug 1961 | |
| 3097578 | Winkler et al. | Jul 1963 | |
| 3265382 | Sherman | Aug 1966 | |
| 5242369 | Eschweiler, Jr. et al. | Sep 1993 | |
| 5246415 | Fuss | Sep 1993 |
| Number | Date | Country |
|---|---|---|
| 0447017 | Jan 1936 | GBX |
| Entry |
|---|
| Xerox Disclosure Journal, Folder/Nester, Robert Hayskar, vol. 8 No. 2, Mar./Apr. 1983, pp. 99-100. |