| Number | Name | Date | Kind |
|---|---|---|---|
| 4908436 | Scheibli | Mar 1990 | |
| 5554733 | Tzikas et al. | Sep 1996 | |
| 5731421 | Tzikas et al. | Mar 1998 | |
| 5750662 | Reichert et al. | May 1998 |
| Number | Date | Country |
|---|---|---|
| 50-157420 | Dec 1975 | JPX |
| Entry |
|---|
| Shirasaki et al., Chemical Abstracts, 84:123388 (1976) Abstract of JP 50-157,420, Dec. 10, 1975. |