| Number | Name | Date | Kind |
|---|---|---|---|
| 3508178 | Chabala et al. | Apr 1970 | |
| 3909570 | Harner et al. | Sep 1975 |
| Number | Date | Country |
|---|---|---|
| 675244 | Dec 1963 | CAX |
| Entry |
|---|
| Japanese Patent Office Design Gazette H1-512, Jul. 11, 1989, Registration No. 629050, (2 pp.). |
| Takamatso Electric Works Bulletin No. 210-83A, (2 pp.). |