A. Wazzan, Nuha, et al. “DFT Calculations of Charge Transfer Complexes of N-Aryl-N’-4-(-P-Anisyl-5-arylazothiazolyl)thiourea Derivatives and Benzoquinones”. Asian Journal of Chemistry, vol. 27, no. 11, July 2015, pp. 3937-50, doi:10.14233/ajchem.2015.18944.