G. A. Wardani, D. D. Pamungkas, W. T. Wulandari, F. Setiawan, and E. Nofiyanti, “Adsorption of Lead(II) Ions using Coconut Fiber’s (Cocos nusifera L.) Activated by Sodium Hydroxide”, J. Akademika Kimia, vol. 9, no. 2, pp. 107-110, May 2020.