Harahap FA, Hutasuhut S, Thamrin T. Development of Flip Book-Based Economics Teaching Materials To Improve The Economic Learning Outcomes of Students In Class Xi Man 2 Deli Serdang In Academic Year 2021/2022. jrssem [Internet]. 2023Jan.19 [cited 2024Nov.19];2(6):938-56. Available from: https://jrssem.publikasiindonesia.id/index.php/jrssem/article/view/356