Buxtorf, R., Steinmann, W., & Kaden, T. A. (1974). Complexes with macrocyclic ligands, III: Pentaco-ordinate metal complexes with 1,4,7,10,12,12 - hexamethyl -1,4,7,10- tetraazacyclotridecane, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane and 1,4,5,8,11,12- hexamethyl-1,4,8,11-tetraazacyclotetradecane. CHIMIA, 28(1), 15. https://doi.org/10.2533/chimia.1974.15_2