1. Merck & Co., Inc., The Merck Index, 14th ed., NJ, USA, 2006, p. 1013.
2. British Pharmacopoeia Commission, BP2010, London, 2010, pp. 1363–1364.
3. EDQM, European Pharmacopoeia 6.0, France, p. 2359.
4. US Pharmacopeial Convention, USP32 NF27, 2009, pp. 2887–2889, 733–736.