| Number | Name | Date | Kind |
|---|---|---|---|
| 2286662 | Weyde et al. | Jun 1942 | |
| 2336327 | Weissberger et al. | Dec 1973 | |
| 2846307 | Woolley | Aug 1958 | |
| 3459548 | Bloom | Aug 1969 | |
| 3482971 | Bloom et al. | Dec 1969 | |
| 3582333 | Yost et al. | Jun 1971 | |
| 3980479 | Fields et al. | Sep 1976 |
| Number | Date | Country |
|---|---|---|
| 2402900 | Aug 1974 | DEX |
| Entry |
|---|
| "Color-forming couplers...", Salminen et al., Research Disclosure #12711 11/1974 pp. 14-15. _ |