High-Accuracy Numerical Approximations to Several Singularly Perturbed Problems and Singular Integral Equations by Enriched Spectral Galerkin Methods. Journal of Mathematical Study, [S. l.], v. 53, n. 2, p. 143–158, 2020. DOI: 10.4208/jms.v53n2.20.02. Disponível em: https://global-sci.com/index.php/jms/article/view/13368. Acesso em: 6 dec. 2025.