Sangeetha, J.E., S. Meenalochani, K. Radha, and D. Chellappa. 2010. “Synthesis and Characterization of Transition Metal Complexes of 12- and 14-Membered Tetraaza Macrocycles”. Asian Journal of Chemistry 20 (6):4749-54. https://asianpubs.org/index.php/ajchem/article/view/19090.