SUN, Longfa; DONG, Yunbai. More on stability of two functional equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 75, n. 6, p. 859–868, 2023. DOI: 10.37863/umzh.v75i6.7121. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/7121. Acesso em: 15 dec. 2025.