Shiku, DJ., Stijns, M., Lintermans, JP., & Vliers, A. (1982). Influence of Age On Atrioventricular-conduction Intervals in Children With and Without Atrial Septal-defect. Journal of Electrocardiology, 15(1), 9-13. https://doi.org/10.1016/S0022-0736(82)80039-3 (Original work published 1982)