Chaiyasith, Suwan, Pachernchai Chaiyasith, and Chutima Septhum. 2015. “Removal of Cadmium and Nickel From Aqueous Solution by Adsorption Onto Treated Fly Ash From Thailand”. Science & Technology Asia 11 (2):13-20. https://ph02.tci-thaijo.org/index.php/SciTechAsia/article/view/41548.