Younis, A. S., K. N. Khurshed, and A. K. Abdullah. “Determination of Aortic Valve Efficiency through Vortex Physical Parameters in Normal, Regurgitate, and Stenotic Valve by Using Doppler-Mode Echocardiography”. Zanco Journal of Medical Sciences (Zanco J Med Sci), vol. 17, no. 2, Aug. 2013, pp. 443-9, doi:10.15218/zjms.2013.0030.