1. M. Negwer, Organisch-Chemische Arzneimittel and ihre Synonyma, Vol. 1, Akad.-Verlag, Berlin (1978), pp. 479, 516.
2. E. Besthoru, Ber., 28, 3151 (1895).
3. E. Besthoru, Ber., 29, 2665 (1896).
4. H. Adkins, J. Am. Chem. Soc., 56, 2425 (1934).
5. L. N. Yakhontov, L. I. Mastafanova, and M. V. Rubtsov, Zh. Obshch. Khim., 30, 519 (1960).