| Number | Name | Date | Kind |
|---|---|---|---|
| 3621611 | Wingerter | Nov 1971 | |
| 3692281 | Clayton | Sep 1972 | |
| 3727347 | Barnes | Apr 1973 | |
| 3803792 | Fulton | Apr 1974 |
| Number | Date | Country |
|---|---|---|
| 2031196 | Jan 1972 | DEX |
| 2705375 | Jun 1976 | DEX |
| 1465465 | Jan 1967 | FRX |
| Entry |
|---|
| Science and Invention, May 1926, p. 54. |