Mandal, W. A. (2018) “Proof without Words: (a+b+c)^2,(a+b-c)^2,(a+b+c)^2-(a+b-c)^2”, Ohio Journal of School Mathematics, 78(1). Available at: https://www.osu.tests.sfulib4.publicknowledgeproject.org/index.php/OJSM/article/view/6216 (Accessed: 29 April 2026).