Fathy, W. M., R. S. Farag, M. El Nawawy, H. Atiaa, and T. Mahdy. “High Performance Liquid Chromatography Method to Detect Tramadol and Sildenafil in the Blood of Rats on Combination Treatment”. INTERNATIONAL JOURNAL OF COMPUTERS &Amp; TECHNOLOGY, vol. 11, no. 6, Nov. 2013, pp. 2682-90, doi:10.24297/ijct.v11i6.3043.