YUNUSOVA, Nigora, et al. “A SENSITIVE SORPTION–SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF CU(II) IONS IN NATURAL WATERS USING PYROCATECHOL BINAFSHA IMMOBILIZED ON A POLYETHYLENE POLYAMINE–POLYACRYLONITRILE (PPF-1) MATRIX”. «ACTA NUUz», vol. 3, no. 3.1, Mar. 2026, pp. 491-4, http://journals.nuu.uz/index.php/actanuuz/article/view/11440.