Oxman, Victor, and Moshe Stupel. “Proof Without Words: Trisection of a Parallelogram’s Diagonal (p. 58)”. Ohio Journal of School Mathematics 84, no. 1 (April 9, 2020). Accessed April 29, 2026. https://www.osu.tests.sfulib4.publicknowledgeproject.org/index.php/OJSM/article/view/7602.