ALIEV, B. A.; KURBANOVA, N. K.; YAKUBOV, Ya. On one boundary-value problem for elliptic differential-operator equations of the second order with quadratic spectral parameter. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 69, n. 6, p. 734–750, 2017. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1732. Acesso em: 5 dec. 2025.