S. D.  Warkad, Santhakumari, B., and Chandewar, A. V., ?Development and validation of a simple and sensitive RP-HPLC method for simultaneous estimation of drospirenone and ethinylestradiol in combined tablet dosage form?, International Journal of Pharmacy and Pharmaceutical Sciences, vol. 4, no. 5, pp. 452-457, 2012.