RUTKAS, A. G. Solvability of semilinear differential equations with singularity. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 60, n. 2, p. 225–239, 2008. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3152. Acesso em: 6 dec. 2025.