Sudirman Sudirman. “Effects of Adding Coal Ash Vs Rice Husk Ash on Compressive Strength of Mortar”. Journal of Engineering, Electrical and Informatics 4, no. 1 (January 31, 2024): 14–30. Accessed November 24, 2024. https://ejurnal.stie-trianandra.ac.id/index.php/jeei/article/view/2785.