| Number | Name | Date | Kind |
|---|---|---|---|
| 3709492 | Baker et al. | Jan 1973 | |
| 3995748 | Looney | Dec 1976 | |
| 4134672 | Burlew et al. | Jan 1979 |
| Entry |
|---|
| IBM Tech. Disc. Bull., vol. 18, No. 9, Feb., 1976, p. 2807. |
| IBM Technical Disclosure Bulletin, vol. 18, No. 10, Mar. 1976, pp. 3160-3161. |
| Research Disclosure Bulletin, Sep. 1979, pp. 497-499, Paper No. 18541. |