O’Neil, J., Hughes, S., Lourie, A., & Zweifler, J. (2008). Effects of echinacea on the frequency of upper respiratory tract symptoms: A randomized, double-blind, placebo-controlled trial. Ann Allergy Asthma Immunol.
Chicago Style CitationO’Neil, Joelle, Susan Hughes, Andrea Lourie, i John Zweifler. "Effects of Echinacea On the Frequency of Upper Respiratory Tract Symptoms: A Randomized, Double-blind, Placebo-controlled Trial." Ann Allergy Asthma Immunol 2008.
Cita MLAO’Neil, Joelle, Susan Hughes, Andrea Lourie, i John Zweifler. "Effects of Echinacea On the Frequency of Upper Respiratory Tract Symptoms: A Randomized, Double-blind, Placebo-controlled Trial." Ann Allergy Asthma Immunol 2008.
Atenció: Aquestes cites poden no estar 100% correctes.