ALIEV, B. A. Solvability of the boundary-value problem for the second-order elliptic differential-operator equation with spectral parameter in the equation and boundary conditions. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 62, n. 1, p. 3–14, 2010. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2839. Acesso em: 27 apr. 2025.