Akhtar, Khurram, et al. “TECHNICAL OVERVIEW OF PERCUTANEOUS TRANS-CATHETER DEVICE OCCLUSION OF VENTRICULAR SEPTAL DEFECTS WITH VARIOUS BRANDS OF SEPTAL OCCLUDERS. EXPERIENCE AT AFIC-NIHD RAWALPINDI”. Pakistan Armed Forces Medical Journal, vol. 69, no. Suppl-3, Nov. 2019, pp. S451-56, https://pafmj.org/PAFMJ/article/view/3561.