Mohamed Yusof, Mohamed Khatif Tawaf, et al. “Feasibility Study of Palm Oil Boiler Ash (POBA) As a Partial Replacement of Sand in Foamed Concrete ”. Scientific Review Engineering and Environmental Sciences (SREES), vol. 31, no. 1, Feb. 2022, pp. 3-13, doi:10.22630/srees.2314.