Landong, Ahmad, et al. “ Pengembangan Bahan Ajar Matematika Materi Bangun Datar Menggunakan Model PBL Terhadap Aktifitas Belajar Siswa Kelas IV SD”. Innovative: Journal Of Social Science Research, vol. 3, no. 2, June 2023, pp. 12784-96, https://j-innovative.org/index.php/Innovative/article/view/1835.