Saxena, M.K., et al. “Complexes of Ni(II), Cu(II), Zn(II), Pd(II) and Cd(II) With 1-Salicylidene-4-Pyrrolidino Thiosemicarbazone”. Asian Journal of Chemistry, vol. 7, no. 2, Mar. 2010, pp. 266-70, https://asianpubs.org/index.php/ajchem/article/view/24281.