Second Hankel Determinant Estimates via Gegenbauer Polynomials. Gulf Journal of Mathematics, [S. l.], v. 24, n. 1, 2026. DOI: 10.56947/y60dvz35. Disponível em: https://www.gjom.org/index.php/gjom/article/view/5118. Acesso em: 21 sep. 2026.