Bi, Jian-Hong, Wen-Tao Bi, Zi-Xian Huang, and Nai-Liang Hu. 2010. “Synthesis and Crystal Structure of a Tetaraazamacrocyclic Compound”. Asian Journal of Chemistry 21 (8):6619-21. https://asianpubs.org/index.php/ajchem/article/view/12373.