H. I. Kandil, M. M. A. el ghany, H. Risk, R. M. Darwish, D. Osama, and M. A. Ibrahim, “Valsalva Maneuver in diastolic heart failure, diastolic dysfunction and systolic heart failure clinically BNP and echocardiography”, J Cardiovasc Med Cardiol, vol. 5, no. 4, pp. 048–052, Oct. 2018.