KUZHEL', S. A. On elements of the Lax-Phillips scattering scheme for $ρ$-perturbations of an abstract wave equation. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 50, n. 12, p. 1615–1629, 1998. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4781. Acesso em: 5 dec. 2025.