M. SHOUKRY, EMAN, et al. “Potentiometric Studies of Binary and Ternary Nickel(II) Complexes Involving Ethylenediamine-N,N&Acute; -Diacetic Acid, Amino Acids and Peptides ”. Asian Journal of Chemistry, vol. 15, no. 1, Mar. 2010, pp. 5-14, https://asianpubs.org/index.php/ajchem/article/view/21493.