Vernitski, Alexei. “A Blind Spot in Undergraduate Mathematics: The Circular Definition of the Length of the Circle, and How It Can Be Turned into an Enlightening Example”. MSOR Connections 20, no. 3 (August 29, 2022): 85–90. Accessed October 19, 2025. https://journals.gre.ac.uk/index.php/msor/article/view/1300.