Palaniandy, S., K. Nizar Ismail, and K. Azizi Mohd Azizli. “Physical and Chemical Characterization of Silica Based Raw Materials from Industrial Waste”. Malaysian Journal of Science, vol. 21, Dec. 2002, pp. 161-4, https://malindojournal.um.edu.my/index.php/MJS/article/view/8881.