SITANGGANG, ANDRI KRISTIANTO. “MENINGKATKAN KEMAMPUAN PEMECAHAN MASALAH MATEMATIKA SISWA SD MELALUI PENDEKATAN OPEN-ENDED”. JURNAL HANDAYANI PGSD FIP UNIMED 2, no. 2 (March 26, 2015). Accessed January 31, 2025. http://103.242.233.34/index.php/handayani/article/view/2029.