| Number | Date | Country | Kind |
|---|---|---|---|
| 54-66997 | May 1979 | JPX |
| Number | Name | Date | Kind |
|---|---|---|---|
| 1853781 | Rider | Apr 1932 | |
| 1895654 | Forrest | Jan 1933 | |
| 3025052 | Gutteling | Mar 1962 | |
| 3580674 | Schunk et al. | May 1971 | |
| 3689150 | Nothmann et al. | Sep 1972 | |
| 4135810 | Walter | Jan 1979 | |
| 4178097 | Sara | Dec 1979 |
| Number | Date | Country |
|---|---|---|
| 1390104 | Apr 1975 | GBX |
| Entry |
|---|
| IBM Technical Disclosure Bulletin, vol. 13, No. 9, Feb. 1971. |