Shiku, DJ., Stijns, M., Lintermans, JP., & Vliers, A. (1981). Atrioventricular-conduction and Right Atrial Volume in Children With and Without Secundum Atrial Septal-defects. British Heart Journal, 46(1), 69-73. https://doi.org/10.1136/hrt.46.1.69 (Original work published 1981)