Hoa, Vu T., Nguyen Q. Thang, Le V. Tan, and Le T.T. Tran. 2023. “Exploring Plant Species in Vietnam for the Production of PH Indicator Paper: Http: www.doi.org 10.26538 Tjnpr V7i10.25”. Tropical Journal of Natural Product Research (TJNPR) 7 (10): 4894-4901. https://tjnpr.org/index.php/home/article/view/2838.