| Number | Date | Country | Kind |
|---|---|---|---|
| 3131980 | Aug 1981 | DEX | |
| 3221479 | Jun 1982 | DEX |
| Number | Name | Date | Kind |
|---|---|---|---|
| 2965533 | Whetstone | Dec 1960 |
| Number | Date | Country |
|---|---|---|
| 1047776 | Dec 1958 | DEX |
| Entry |
|---|
| Derwert Japanese, 1/9/69-1/14/69, vol. 8, No. 2. |
| Derwert Japanese, 3/14/68-3/19/68, vol. 7, No. 11. |
| Chemical Abstracts, vol. 52, pp. 8937-8940. |