RAJPER, A.D., et al. “Spectrophotometric and Liquid Chromatographic Determination of Dopamine from Pharmaceutical Preparations Using 2-Hydroxynaphthaldehyde As Derivatizing Reagent”. Asian Journal of Chemistry, vol. 19, no. 6, Mar. 2010, pp. 4817-24, https://asianpubs.org/index.php/ajchem/article/view/20026.