S. I. Zherebtsov, N. V. Malyshenko, L. V. Bryukhovetskaya, S. Y. Lyrshchikov, and Z. R. Ismagilov, “Copper Sorption by Coal Substances from Aqueous Solutions”, Eurasian Chem.-Technol. J., vol. 17, no. 2, pp. 165–171, Apr. 2015.