Rennita, Oktavia Dwi. “The Differences of Improving Communication Ability and Mathematical Concepts Understanding Between Students That Given Problem Based Learning and Discovery Learning at SMP Swasta Al-Hikmah Medan”. Advances in Social Sciences Research Journal 5, no. 10 (November 5, 2018). Accessed May 28, 2026. https://scholarpublishing.org/journals/index.php/ASSRJ/article/view/3234.