Samsudin, Muhammad Hasnolhadi, et al. “Optimisation on the Hybridisation Ratio of Pulverised Fuel Ash and Ground Granulated Blast Furnace Slag (PFA - GGBS) for the Fabrication of Geopolymer Mortar”. Journal of Engineering Technology and Applied Physics, vol. 5, no. 2, Sept. 2023, pp. 1-4, doi:10.33093/jetap.2023.5.2.1.