Jinnapat , A. ., and A. . Rattanasing. “A Study of Absorption Capacity of Zinc Ions onto Coffee Residue Activated Carbon”. NKRAFA JOURNAL OF SCIENCE AND TECHNOLOGY, vol. 17, no. 2, Dec. 2021, pp. 69-78, https://ph02.tci-thaijo.org/index.php/nkrafa-sct/article/view/245521.