| Number | Name | Date | Kind |
|---|---|---|---|
| 404790 | Knaus | Jun 1889 | |
| 427475 | Knaus | May 1890 | |
| 814165 | Rea et al. | Mar 1906 | |
| 2129637 | Atwood et al. | Sep 1938 | |
| 2774644 | Patterson | Dec 1956 | |
| 3524616 | Marschak | Aug 1970 | |
| 3544187 | Hils | Dec 1970 |
| Entry |
|---|
| IBM.RTM. Technical Disclosure Bulletin vol. 21, No. 5, Oct. 1978. |