EL-SAYED, A. M. A.; HASHEM, H. H. G.; AL-ISSA, S. M. Analytical study of some self-referred or state dependent functional equations. Methods of Functional Analysis and Topology, [S. l.], v. 28, n. 1, p. 50–57, 2022. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/818. Acesso em: 15 dec. 2025.