Tambichik, M. A., A. A. Abdul Samad, N. Mohamad, A. Z. Mohd Ali, M. A. Othuman Mydin, M. Z. Mohd Bosro, and M. A. Iman. “Effect of Combining Palm Oil Fuel Ash (POFA) and Rice Husk Ash (RHA) As Pozzolan to the Compressive Strength of Concrete”. International Journal of Integrated Engineering, vol. 10, no. 8, Dec. 2018, https://publisher.uthm.edu.my/ojs/index.php/ijie/article/view/3077.