Oxman, Victor. “Proof Without Words: One Elegant Relationship Between the Angles Formed in an Acute Triangle”. Ohio Journal of School Mathematics 91, no. 1 (July 19, 2022): 1. Accessed April 30, 2026. https://www.osu.tests.sfulib4.publicknowledgeproject.org/index.php/OJSM/article/view/8844.