1. European Pharmacopoeia, fifth ed., supplement 5.2,2005
2. United States Pharmacopeia, 29th revision, second supplement,2006
3. Guidance for Industry, Drug Product, Chemistry, Manufacturing, and Controls Information,2003
4. Commission Directive 2003/63/EC;Off. J. Eur. Union,2003
5. European Pharmacopoeia,2004