Shanmukhappa, S., et al. “Synthesis, Spectral, Magnetic and Antibacterial Properties of Copper(II) Complexes of Quaternary and Tertiary N-Donor Ligands”. Asian Journal of Chemistry, vol. 20, no. 7, Mar. 2010, pp. 5259-66, https://asianpubs.org/index.php/ajchem/article/view/12941.