Al Bakri, A. M. ., H. Kamarudin, M. Bnhussain, I. K. . Nizar, and W. Mastura. “Mechanism and Chemical Reaction of Fly Ash Geopolymer Cement- A Review”. Journal of Asian Scientific Research, vol. 1, no. 5, Sept. 2011, pp. 247-53, https://archive.aessweb.com/index.php/5003/article/view/3292.