Zein, Rahmiana, et al. “Chemical Modification of Some Functional Groups on Marine Algae (Sargassum Crasifolium) Powder for the Evaluation of Lead(II) Uptake”. Asian Journal of Chemistry, vol. 21, no. 3, Mar. 2010, pp. 2032-6, https://asianpubs.org/index.php/ajchem/article/view/18695.