.-. Saloma, .-. Hanafiah, T. M. Amanda, and A. S. Budiarti, “Characteristics of Foamed Concrete Utilizing Rice Husk Ash with Foam Percentage Variation”, Int. J. Adv. Sci. Eng. Inf. Technol., vol. 8, no. 5, pp. 1969–1975, Oct. 2018.