Krishnan, G., and N. Babu. “Synthesis and Characterization of Manganese(II), Cobalt(II), Nickel(II), Copper(II), Zinc(II) and Cadmium(II) Complexes of a Polydentate Ligand”. Asian Journal of Chemistry, vol. 16, no. 2, Aug. 2016, pp. 942-6, https://asianpubs.org/index.php/ajchem/article/view/14598.