| Number | Name | Date | Kind |
|---|---|---|---|
| 3471312 | Muenchinger et al. | Oct 1969 | |
| 3481659 | Rosenberg | Dec 1969 | |
| 3965888 | Bender | Jun 1976 | |
| 4087154 | Menzel | May 1978 |
| Number | Date | Country |
|---|---|---|
| 1077881 | Aug 1967 | GBX |
| Entry |
|---|
| IBM. Tech. Bulletin, Hist. Spec. Slide, vol. 12, No. 4, Sep. 1960, p. 573. |