Hardoko, Hardoko, et al. “Antibacterial Activity of Cough Suppressant Functional Drink from Betel Leaves (Piper sarmentosum), Lime (Citrus Aurantifolia) and Honey: doi.org 10.26538 Tjnpr V4i10.7”. Tropical Journal of Natural Product Research (TJNPR), vol. 4, no. 10, Oct. 2020, pp. 695-02, https://tjnpr.org/index.php/home/article/view/1023.