Nazir, Hasan, Cengiz Arici, Ahmet Aydin, and Hamza Yilmaz. 2010. “Synthesis and Crystal Structure of [(2-Substituted-Phenylamino)-(2-Hydroxy-Phenyl)- Methyl]-Phosphonic Acid Diethyl Esters”. Asian Journal of Chemistry 18 (3):2231-36. https://asianpubs.org/index.php/ajchem/article/view/20979.