صالح ز. “Methyl Acetoacetate As a Coupling Agent InSpectrophotometric Determination of P- Aminobenzoic Acid by Azo-Dye Formation Reaction”. College of Basic Education Research Journal, vol. 5, no. 3, Aug. 2007, pp. 192-06, https://stats.uomosul.edu.iq/index.php/berj/article/view/39215.