Sitanggang AK, Lubis A, Elisa TS. PENGEMBANGAN MODEL DESIGN DIDACTIC RESEARCH (DDR) UNTUK MENGATASI HAMBATAN BELAJAR (LEARNING OBSTACLE) MATEMATIKA. JH [Internet]. 2024 Jun. 20 [cited 2025 Jan. 31];15(1):1-6. Available from: http://103.242.233.34/index.php/handayani/article/view/60118