HARTMANN, Julia; HERZOG, Moritz; FRITZ, Annemarie. Zero – an Uncommon Number: Preschoolers‘ Conceptual Understanding of Zero. International Electronic Journal of Elementary Education, [S. l.], v. 14, n. 3, p. 353–361, 2022. Disponível em: https://www.iejee.com/index.php/IEJEE/article/view/1740. Acesso em: 4 aug. 2026.