Mehatab Begum, F.R., et al. “Synthesis, Spectroscopic, Electrochemical and Biological Studies of Co(II), Ni(II) and Cu(II) Complexes of 2-Hydroxybenzylidene-2’-Hydroxyaniline”. Asian Journal of Chemistry, vol. 23, no. 12, Sept. 2011, pp. 5258-60, https://asianpubs.org/index.php/ajchem/article/view/11095.