| Number | Name | Date | Kind |
|---|---|---|---|
| 2083308 | Senn | Jun 1937 | |
| 2289413 | Ellis et al. | Jul 1942 | |
| 3122410 | Mueller et al. | Feb 1964 | |
| 3232693 | Lange et al. | Feb 1966 | |
| 3342803 | Artz et al. | Sep 1967 |
| Number | Date | Country |
|---|---|---|
| 533,439 | Feb 1941 | UK |
| Entry |
|---|
| Venkataraman, K., "The Chemistry of Synthetic Dyes," vol. III, (Academic Press, 1970), pp. 434-437. |