Mohd Sari, K. A., S. Mat, K. Badri, and A. R. M. Sani. “Properties of Structural Lightweight Concrete Filled With Palm-Based Polyurethane”. International Journal of Integrated Engineering, vol. 6, no. 1, Sept. 2014, https://penerbit.uthm.edu.my/ojs/index.php/ijie/article/view/881.