Костенко, Є. Є., and О. М. Бутенко. “Solid-Phase Spectrophotometric Determination of Нg (II) Using Xylenol Orange”. Eastern-European Journal of Enterprise Technologies, vol. 4, no. 6(70), Aug. 2014, pp. 44-48, doi:10.15587/1729-4061.2014.26201.