Oxman, V. and Stupel, M. (2020) “Proof Without Words: Trisection of a Parallelogram’s Diagonal (p. 58)”, Ohio Journal of School Mathematics, 84(1). Available at: https://www.osu.tests.sfulib4.publicknowledgeproject.org/index.php/OJSM/article/view/7602 (Accessed: 30 April 2026).