7.Pfaffenrath V, Diener HC, Pageler L, Peil H, Aicher B. OTC analgesics in headache treatment: open-label phase vs randomized double-blind phase of a large clinical trial. Headache 2009;49(5):638–45. http://www.ncbi.nlm.nih.gov/pubmed/19472437
8.Hu Z, Yang X, Ho PC, Chan SY, Heng PW, Chan E, Duan W, Koh HL, Zhou S. Herb-drug interactions: a literature review. Drugs. 2005;65(9):1239-82. http://www.ncbi.nlm.nih.gov/pubmed/15916450
9.Abebe W. Herbal medication: potential for adverse interactions with analgesic drugs. J Clin Pharm Ther. 2002 Dec;27(6):391-401. http://www.ncbi.nlm.nih.gov/pubmed/12472978
10.Agency for Healthcare Research and Quality. Comparative Effectiveness of Dietary Supplement Versus No Dietary Supplement Use in Adults Taking Cardiovascular Drugs. April 2012. http://www.effectivehealthcare.ahrq.gov/ehc/products/223/596/DietarySupplement_Amended_Protocol_20110428.pdf