KARABASH, I. M. On ordinary differential operators of an odd order nonsimilar to normal operators. Methods of Functional Analysis and Topology, [S. l.], v. 7, n. 1, p. 17–27, 2001. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/135. Acesso em: 17 dec. 2025.