M. AWADALLAH., RAMADAN. “Preparation and Characterization of lron(II, III), Cobalt(II, III) and Nickel(II)-Complexes of 2,2-Dipyridyl”. Asian Journal of Chemistry, vol. 6, no. 2, June 2010, pp. 393-04, https://asianpubs.org/index.php/ajchem/article/view/24559.