Sembiring, Iga Marisa, et al. “Pengembangan Bahan Ajar Matematika Materi Bilangan Bulat Menggunakan Model Pbl Terhadap Minat Belajar Siswa Kelas IV SD”. Innovative: Journal Of Social Science Research, vol. 3, no. 2, June 2023, pp. 12827-3, https://j-innovative.org/index.php/Innovative/article/view/1834.