Hanyotee, S., and M. Chareonpenich. “Synthesis of High Purity ZSM-5 Zeolite from Lignite Fly Ash via Two-stage Process”. Engineering and Applied Science Research, vol. 31, no. 4, Mar. 2013, pp. 409-24, https://ph01.tci-thaijo.org/index.php/easr/article/view/6774.