| Number | Date | Country | Kind |
|---|---|---|---|
| 2918778 | May 1979 | DEX |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3471473 | Walker | Oct 1969 | |
| 3699099 | Drukker et al. | Oct 1972 | |
| 3931158 | Freedman | Jan 1976 | |
| 4045445 | Hardy et al. | Aug 1977 |
| Number | Date | Country |
|---|---|---|
| 2918832 | May 1979 | DEX |
| 834281 | May 1960 | GBX |
| Entry |
|---|
| Hunziker et al. Helv. Chim. Acta 49 (1966), pp. 1433-1439. |