1. Williamson EM. Synergy and other interactions in phytomedicines. Phytomedicine 2001 Sep; 8 (5): 401–9
2. Document DPM/79.1. 1978 Oct 9-13;M Attiso,1978
3. European Directorate for the Quality of Medicines. European pharmacopoeia. 6th ed. Strasbourg: Council of Europe, 2008
4. Directive 2004/24/EC of the European Parliament and of the Council of 31 March 2004 amending, as regards traditional herbal medicinal products, Directive 2001/83/EC on the Community code relating to medicinal products for human use (Official Journal L 136, 30/4/2004, p. 85-90) [online]. Available from URL: http://ec.europa.eu/enterprise/pharmaceuticals/eudralex/vol-1/dir_2004_24/dir_2004_24_en.pdf [Accessed 2008 Feb 27]
5. Herbal Medicinal Products Committee (HMPC). Guideline on specifications: test procedures and acceptance criteria for herbal substances, herbal preparations and herbal medicinal products/traditional herbal medicinal products. CPMP/ QWP/2820/00 Rev 1. London 2006 [online]. Available from URL: http://www.emea.europa.eu/pdfs/human/qwp/282000en.pdf [Accessed 2008 Feb 27]