1. Reynolds, J. E. F., ed. 1989.Martindale, The Extra Pharmacopoeia, pp. 112 & 215London: 29th edn. The Pharmaceutical Press.
2. 1988.The British Pharmacopoeia (BP), pp. 40–42. 625London: H. M. Stationery Office.
3. 1990.The United States Pharmacopeia (USP) XXII (NF XVII), pp. 88–91. Easton-Pennsylvania: US Pharmacopeial Convention.