E. Ivashchenko, R. Omarova, and K. Ospanov, “The peculiarities of the spatial structure of Cd(II), Hg(II), In(III), Tl(III), Sn(II) AND Pb(II) metallic salts complex compounds”, Chemical Bulletin of Kazakh National University, vol. 64, no. 4, pp. 100-104, Dec. 2011.