Babu, N. “Synthesis and Characterisation of Cobalt(II), Nickel(II), Copper(II), Zinc(II) and Cadmium(II) Complexes of N,N’-Propylene-bis(3-Carboxypropenamide)”. Asian Journal of Chemistry, vol. 16, no. 3, June 2016, pp. 1791-5, https://asianpubs.org/index.php/ajchem/article/view/14467.