N. A. Leonova, O. I. Yurchenko, and A. S. Batrak, “Spectrophotometric determination of concentrations of Co (II) and Ni (II) in complex with 1- (2-pirydylazo) -2-naphthol in aqueous micellar medium”, Khark. Univ. Bull. Chem. Ser., no. 24, pp. 153-160, Oct. 2014.