Tsvetkova, B., and L. Peikova. “HPLC METHOD FOR SIMULTANEOUS DETERMINATION OF KETOPROFEN AND PRESERVATIVES IN GEL FORMULATION”. International Journal of Pharmacy and Pharmaceutical Sciences, vol. 6, no. 11, Nov. 2014, pp. 199-02, https://journals.innovareacademics.in/index.php/ijpps/article/view/2960.