| Number | Date | Country | Kind |
|---|---|---|---|
| 77 11561 | Apr 1977 | FRX |
| Number | Name | Date | Kind |
|---|---|---|---|
| 2594166 | Hennink | Apr 1952 | |
| 3425184 | Heliot | Feb 1969 | |
| 3918703 | Mano et al. | Nov 1975 | |
| 3934717 | Katagiri et al. | Jan 1976 | |
| 3982637 | Roetgerink | Sep 1976 |
| Number | Date | Country |
|---|---|---|
| 1088877 | Sep 1960 | DEX |
| 364367 | Jan 1932 | GBX |
| Entry |
|---|
| IBM Technical Disclosure Bulletin-vol. 16, No. 11, (Apr. 1974), pp. 3535-3537. |