1. United States Pharmacopoeia 23, National Formulary 18, 1991, pp. 35.
2. British Pharmacopoeia, 1993, vol. 1, pp. 24.
3. European Pharmacopoeia, 1997, 3rd edition, pp. 346.
4. P. Ray, Indian J. Pharm. Sci., 47 (2) (1985) 34–36.
5. Y. Pramar, V. Das Gupta, T. Zerai, Drug Dev. Ind. Pharm. 16 (10) (1990) 1687–1695.