G. Rao, N. Kumar, T. Rao, K. Rao, and N. V. Simhadri, “Chemical Speciation of Binary Complexes of Pb(Ii), Cd(Ii) and Hg(Ii) with L-Methionine in Propylene Glycol -Water Mixture”, JPRC, vol. 2, no. 1, pp. 61-68, Jul. 2015.