ACIKGOZ, M.; ARACI, S.; ŞEN, E. Spectral problem for Sturm – Liouville operator with retarded argument which contains a spectral parameter in boundary condition. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 68, n. 8, p. 1102–1114, 2016. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1905. Acesso em: 5 dec. 2025.