M-fold symmetric biunivalent functions defined by Gegenbauer polynomials: novel subclasses and coefficient bounds. Gulf Journal of Mathematics, [S. l.], v. 22, n. 2, 2026. DOI: 10.56947/gjom.v22i2.3961. Disponível em: https://gjom.org/index.php/gjom/article/view/3961. Acesso em: 23 aug. 2026.