1. Waksman SA, Lechevalier HA (1949) Science 109:305–310
2. Funk W, Kupper T, Wirtz A, Netz S (1994) J Planar Chromatogr 7:10–17
3. (2002) European Pharmacopoeia. European Department for the Quality of Medicines, Strasbourg, France
4. (2002) United States Pharmacopoeia. United States Pharmacopeial Convention, Rockville, Md.
5. Yang M, Tomellini SA (2001) J Chromatogr A 939:59–67