D. M. Salh, “Spectrophotometric Determination of Isoptin (Verapamil Hydrochloride) in Pharmaceutical Preparations”, IHJPAS, vol. 23, no. 3, pp. 106–115, May 2017, Accessed: Mar. 27, 2025. [Online]. Available: https://jih.uobaghdad.edu.iq/index.php/j/article/view/913