Janzen, M., Cheung, C., Hawkins, N., Raudzus, J., Geller, J., Lam, P., & Krahn, A. (1969). Changes to the electrocardiogram during exercise in anorexia nervosa. Journal of Electrocardiology, 61, 99-105. https://doi.org/10.1016/j.jelectrocard.2020.06.012 (Original work published 1969)