IL'KIV, V. S.; STRAP, N. I. Solvability of the Nonlocal Boundary-Value Problem for a System of Differential-Operator Equations in the Sobolev Scale of Spaces and in a Refined Scale. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 67, n. 5, p. 611–624, 2015. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2009. Acesso em: 14 apr. 2025.