Nizar Ismail, Khairul, Mohd Sobri Idris, Kamarudin Hussin, and Khairun Azizi Mohd Azizli. 2002. “The Microstructure of Lightweight Aggregates Made of Pulverised Fuel Ash”. Malaysian Journal of Science 21 (December):177-79. https://ajba.um.edu.my/index.php/MJS/article/view/8884.