KIM, S. H. On the stability of a nonic functional equation in quasi-normed spaces. JOURNAL OF ADVANCES IN PHYSICS, [S. l.], v. 12, n. 3, p. 4368–4374, 2016. DOI: 10.24297/jap.v12i3.47. Disponível em: https://rajpub.com/index.php/jap/article/view/47. Acesso em: 4 may. 2024.