“H.A. Snellen, Two Pioneers of Electrocardiography. The Correspondence Between Einthoven and Lewis from 1908-1926”. BMGN - Low Countries Historical Review 101, no. 2 (January 1, 1986): 259–260. Accessed July 2, 2024. https://ojstest.minions.amsterdam/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-102951.