Ali, Faraat, et al. “UV-Visible First Order Derivative Spectrophotometric Method Development and Validation for Simultaneous Estimation of Amitriptyline Hydrochloride and Chlordiazepoxide in Tablet Dosage Form”. Asian Journal of Chemistry, vol. 28, no. 12, Sept. 2016, pp. 2632-4, doi:10.14233/ajchem.2016.20032.