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 May 4, 2024. https://ohiomathjournal.org/index.php/OJSM/article/view/7602.