1. Martindale, In: K. Parfitt (Ed.), The Complete Drug Reference, 32nd edition. Massachusetts, 1999, p. 896.
2. The British Pharmacopoeia, HMSO, London, 2000, Vol. I, p. 780 and Vol. II, p. 573, 574.
3. The United States Pharmacopoea XXIII. The USP Convention, Rockville, 1995, p. 866.
4. The European Pharmacopoeia, Council of Europe, Strasburg, (2001), pp. 1039–1040.