Kharat, Rekha, et al. “Estimation of Tramadol Hydrochloride in Bulk and Formulation by Second Order Derivative Area Under Curve UV-Spectrophotometric Methods”. International Journal of Advances in Scientific Research, vol. 1, no. 7, Sept. 2015, pp. 308-12, https://doi.org/10.7439/ijasr.v1i7.1989.