Ramangkoon, Sumontha, et al. “PREPARATION OF RICE STRAW ACTIVATED CHARCOAL BY 2- STEP H3PO4 ACTIVATION”. International Journal of Pharmacy and Pharmaceutical Sciences, vol. 8, no. 4, Apr. 2016, pp. 218-21, https://www.journals.innovareacademics.in/index.php/ijpps/article/view/10741.