RASSIAS, J. M.; XU, T. Z.; XU, W. X. A generalized mixed type of quartic, cubic, quadratic and additive functional equation. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 63, n. 3, p. 399–415, 2011. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2725. Acesso em: 5 dec. 2025.