Madiyono, B., H. Trisnohadi, and M. Affandi. “HIS Bundle Electrocardiogram in Children With Secundum Atrial Defects and Patent Ductus Arteriosus”. Paediatrica Indonesiana, Vol. 21, no. 1-2, Feb. 1981, pp. 1-10, doi:10.14238/pi21.1-2.1981.1-10.