| Number | Name | Date | Kind |
|---|---|---|---|
| 2803656 | Ahlbrecht et al. | Aug 1957 | |
| 3445491 | Pacini | May 1969 | |
| 4125671 | Magazzu | Nov 1978 |
| Number | Date | Country |
|---|---|---|
| 0040923 | Dec 1981 | EPX |
| Entry |
|---|
| Conant, James Bryant et al., The Chemistry of Organic Compounds 4th ed. (1952) MacMillan, Publ. at p. 335. |