Songkanam, B., A. Wongsa, V. Sata, and K. Wantala. “Characterizations and Its Efficiency on Dye removal of Fly Ash Mixed with Titanium Dioxide Photocatalyst”. Frontiers in Engineering Innovation Research, vol. 18, no. 1, June 2020, pp. 101-10, https://ph01.tci-thaijo.org/index.php/jermutt/article/view/241889.