GNYP, E. V.; KODLYUK, T. I.; MIKHAILETS, V. A. Fredholm Boundary-Value Problems with Parameter in Sobolev Spaces. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 67, n. 5, p. 584–591, 2015. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2006. Acesso em: 5 dec. 2025.