HOSSEIN ROUNAGHI, GHOLAM, et al. “Competitive Transport Studies of Seven Metal Cations Through Bulk Liquid Membrane Using 1,4-Dioxa- 7,10-Dithiacyclododecane-2,3-Dione”. Asian Journal of Chemistry, vol. 21, no. 5, Mar. 2010, pp. 3577-8, https://asianpubs.org/index.php/ajchem/article/view/17334.