| Number | Name | Date | Kind |
|---|---|---|---|
| 1262743 | Bronson | Apr 1918 | |
| 1319652 | Korns | Oct 1919 | |
| 1516911 | Canfield et al. | Nov 1924 | |
| 2795144 | Morse | Jun 1957 | |
| 3075038 | Schinske | Jan 1963 | |
| 3297816 | Waddington | Jan 1967 | |
| 3299766 | Gould et al. | Jan 1967 | |
| 3448223 | Thorsman | Jun 1969 | |
| 3724706 | Slocum | Apr 1973 | |
| 4180228 | Snyder et al. | Dec 1979 |
| Number | Date | Country |
|---|---|---|
| 905344 | Jul 1972 | CAX |
| 2516013 | Dec 1975 | DEX |
| Entry |
|---|
| Electrical Construction and Maintenance-vol. 76, No. 1, Jan. 1977, p. 112. |