Nomanbhay, S. M., and K. Palanisamy. “Removal of Heavy Metal from Industrial Wastewater Using Chitosan Coated Oil Palm Shell Charcoal”. Electronic Journal of Biotechnology, vol. 8, no. 1, Apr. 2005, pp. 0-0, https://preprints.pucv.cl/index.php/ejbiotechnology/article/view/v8n1-7.