Zainudin, A., Sia, C. K., Ong, P., Narong, O. L. C., Azlan, M. A., & Lee, W. K. (2019). Performance Properties Optimization of Triaxial Ceramic-Palm Oil Fuel Ash By Employing Taguchi Grey Relational Analysis. International Journal of Integrated Engineering, 11(1). https://penerbit.uthm.edu.my/ojs/index.php/ijie/article/view/3275