S. Y. Prabawati, J. Jumina, S. J. Santosa, and M. Mustofa, “The Utilization of Poly-37,40-diallyl-38,39,41,42,-tetrahydroxycalix[6]arenes Compound as Adsorbent for Heavy Metal Cations Cd(II), Cr(III) and Cu(II)”, JKR, vol. 5, no. 2, pp. 94–99, Dec. 2020.