I. Kuznetsov, H. Naumenko, N. Reznichenko, A. Kostiuk, R. Savyak, and D. Oleynikov, “Development and validation of method for quantitative determination of sildenafil and n-desmethyl sildenafil by HPLC-MS/MS in human blood plasma”, ScienceRise: Pharmaceutical Science, no. 1 (5), pp. 22–32, Feb. 2017.