KESKIN, B.; OZKAN, S. A. Spectral problem for discontinuous integro-differential operator. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 64, n. 2, p. 277–282, 2012. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2575. Acesso em: 6 dec. 2025.