MARTÍNEZ LEÓN, V. A.; AZEVEDO SCÁRDUA, B. C. Frobenius methods for analytic second order linear partial differential equations. Selecciones Matemáticas, [S. l.], v. 10, n. 02, p. 210 - 248, 2023. DOI: 10.17268/sel.mat.2023.02.01. Disponível em: https://revistas.unitru.edu.pe/index.php/SSMM/article/view/5433. Acesso em: 13 may. 2024.