Mahmood, M, et al. “Doppler Evaluation of Left to Right Shunt (Qp Qs) in Patients With Isolated Ventricular Septal Defect (Vsd)”. Mymensingh Medical Journal, vol. 16, no. 2, Oct. 2007, pp. 181-86, https://banglajol.info/index.php/MMJ/article/view/391.