SHEREMETA, M. M. On the eigenvalues of the fredholm operator. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 48, n. 1, p. 116–123, 1996. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5369. Acesso em: 6 dec. 2025.