Chokpaisarn, Julalak, et al. “Phyllencit Mixture, a Combination of Medicinal Herbs, As an Antitussive Agent for Acute Cough Treatment: A Pilot Pre-Post Clinical Study: doi.org 10.26538 Tjnpr V5i8.9”. Tropical Journal of Natural Product Research (TJNPR), vol. 5, no. 8, Aug. 2021, pp. 1375-81, https://tjnpr.org/index.php/home/article/view/442.