El-Haty, M.T., and A.H. Amrallah. 2010. “Spectral Properties and Acidity Constants of Some Schiff Bases Derived From Salicylaldehyde and Phenylenediamine ”. Asian Journal of Chemistry 2 (4):389-98. https://asianpubs.org/index.php/ajchem/article/view/25336.