| Number | Name | Date | Kind |
|---|---|---|---|
| 2521267 | Tiganik | Sep 1950 | |
| 2985678 | Chappelow | May 1961 | |
| 4683321 | Nelson | Jul 1987 | |
| 4888436 | Shiozawa et al. | Dec 1989 | |
| 4897501 | Takatsuna et al. | Jan 1990 | |
| 4921988 | Takatsuna et al. | May 1990 |
| Number | Date | Country |
|---|---|---|
| 598444 | May 1960 | CAX |
| 573906 | Dec 1945 | GBX |
| 668532 | Mar 1952 | GBX |
| Entry |
|---|
| Ryan, John W., J. Amer. Chem. Soc., 84:4730-34, 1962. |