Hong Bi, Jian, et al. “Synthesis and Crystal Structure of the One-Dimensional Supramolecular Tetraazamacrocyclic Copper(II) Compound”. Asian Journal of Chemistry, vol. 18, no. 3, Mar. 2010, pp. 2365-70, https://asianpubs.org/index.php/ajchem/article/view/21026.