Putri, Fany. “Penelitian Teori Perkembangan Kognitif Piaget Terhadap Hukum Kekekalan Materi”. PRISMA, Prosiding Seminar Nasional Matematika 6 (March 12, 2023): 275-279. Accessed December 19, 2024. https://journal.unnes.ac.id/sju/prisma/article/view/66924.