“Preparation and Characterization of P-Sulfonated Calix[4]arene Functionalized Chitosan Hydrogel Beads and Their Preliminary Adsorption Study towards Removal of Lead(II) and Zinc(II) Ions”. 2020. Malaysian Journal of Fundamental and Applied Sciences 16 (4): 429-32. https://doi.org/10.11113/mjfas.v16n4.1765.