| Number | Name | Date | Kind |
|---|---|---|---|
| 204502 | Osselin et al. | Jun 1878 | |
| 526182 | Fritsche | Sep 1894 | |
| 784125 | Sanden | Mar 1905 | |
| 1190831 | Werner | Jul 1916 | |
| 3304708 | Baehni | Feb 1967 | |
| 3672352 | Summers | Jun 1972 |
| Entry |
|---|
| Kubo, "IEEE Transactions on Biomedical Engineering," vol. 17, No. 2, Apr. 1970, pp. 163-166. |