Gurley, B. J., Swain, A., Williams, D. K., Barone, G., & Battu, S. K. (2008). Gauging the clinical significance of P-glycoprotein-mediated herb-drug interactions: Comparative effects of St. John's wort, echinacea, clarithromycin, and rifampin on digoxin pharmacokinetics.

Gurley, Bill J., Ashley Swain, D. Keith Williams, Gary Barone, ja Sunil Kumar Battu. Gauging the Clinical Significance of P-glycoprotein-mediated Herb-drug Interactions: Comparative Effects of St. John's Wort, Echinacea, Clarithromycin, and Rifampin On Digoxin Pharmacokinetics. 2008.

Gurley, Bill J., et al. Gauging the Clinical Significance of P-glycoprotein-mediated Herb-drug Interactions: Comparative Effects of St. John's Wort, Echinacea, Clarithromycin, and Rifampin On Digoxin Pharmacokinetics. 2008.