Kats, E. M., T. G. Kuzmina, and I. N. Gromjak. “Sorption of Heavy Metals on Organozeolite - Clinoptilolite Modified With Polyethylenimine from Weak Acid Solution”. Sorbtsionnye I Khromatograficheskie Protsessy, Vol. 19, no. 6, Dec. 2019, pp. 656-62, doi:10.17308/sorpchrom.2019.19/2226.