| Number | Date | Country | Kind |
|---|---|---|---|
| 2423536 | May 1974 | DT |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3532738 | Wilson et al. | Oct 1970 | |
| 3646136 | Hoegerle et al. | Feb 1972 | |
| 3806537 | Dorschner et al. | Apr 1974 | |
| 3867426 | Olin et al. | Feb 1975 | |
| 3897493 | Teach | Jul 1975 |
| Entry |
|---|
| Jacobs et al., J.A.C.S. 39, p. 2438. |