Hossein Rounaghi, Gholam, et al. “Studies on the Macrocycle Mediated Transport in a Bulk Liquid Membrane System of Transition Metal Cations”. Asian Journal of Chemistry, vol. 23, no. 7, Mar. 2011, pp. 3177-82, https://asianpubs.org/index.php/ajchem/article/view/10550.