B. Dikran, Sarmad, et al. “Uni and Multivariate Optimization for the Spectrophotometric Determination of Cimetidine Drug via Charge-Transfer Complex Formation”. Ibn AL-Haitham Journal For Pure and Applied Sciences, vol. 28, no. 3, Mar. 2017, pp. 113-28, https://jih.uobaghdad.edu.iq/index.php/j/article/view/147.