K. Dawood, Saad, and Sahbaa A. Al-Sabaawi. 1999. “Investigation of New Tetra Dentate Macrocyclic [N4] Ligand and it’s Complexes With Transition Metal’s”. Journal of Education and Science (JES) 24 (2):22-27. https://doi.org/10.33899/edusj.1999.58727.