Kiew, P. L., and J. F. Toong. “Screening of Significant Parameters Affecting Zn (II) Adsorption by Chemically Treated Watermelon Rind”. Progress in Energy and Environment, vol. 6, Sept. 2018, pp. 19-32, https://www.akademiabaru.com/submit/index.php/progee/article/view/1048.