Muralia Hustim, Purwanto, Sandri Linna Sengkey, Rita Irmawaty,. 2021. “Study of Compressive Strength and Durability of Fly Ash and Trass Based Geopolymer Mortar”. Design Engineering, November, 9246-60. http://thedesignengineering.com/index.php/DE/article/view/5969.