Piyamongkala, kowit and วัจนะรัตน์ พ. (2017) “Adsorption of copper and lead ions by chitosan powder and sodium tripolyphosphate-modified chitosan resin: Kinetics, mechanism and mass transfer”, Naresuan University Engineering Journal. Phitsanulok, Thailand, 12(1), pp. 83–96. doi: 10.14456/nuej.2017.4.