Yusoff, Harunsyah, Nik Meriam Sulaiman, and Mohd Kheireddine Aroua. 2004. “Ultra Filtration Using Gas Sparging Technique for Treatment of Natural Rubber Effluent”. Malaysian Journal of Science 23 (December):177-84. http://ojie.um.edu.my/index.php/MJS/article/view/9052.