| Number | Date | Country | Kind |
|---|---|---|---|
| 3903455 | Feb 1989 | DEX |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3758470 | Ackermann et al. | Sep 1973 | |
| 4935500 | Omura et al. | Jun 1990 |
| Number | Date | Country |
|---|---|---|
| 0280139 | Aug 1988 | EPX |
| 62-192467 | Aug 1987 | JPX |
| 63-05065 | Jul 1988 | JPX |
| Entry |
|---|
| Patent Abstracts of Japan, C. Field, vol. 12, No. 47 (C-475) (2894) (3/12/88). |