1. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2651880/?tool=pubmed
2. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2330043/?tool=pmcentrez
3. The Open Complementary Medicine Journal
4. http://www.ncbi.nlm.nih.gov/pubmed/2912010
5. http://www.jissn.com/content/7/1/5