| Number | Name | Date | Kind |
|---|---|---|---|
| 1659952 | Hurley | Feb 1928 | |
| 3734509 | Glass et al. | May 1973 | |
| 4409277 | Michel | Oct 1983 | |
| 4681324 | Karabed et al. | Jul 1987 | |
| 5259907 | Soules et al. | Nov 1993 | |
| 5465975 | Shull et al. | Nov 1995 |
| Entry |
|---|
| "Lightless Light", Scientific American, Philip H. Smith, pp. 324-327, Dec. 1940. |