PETRINA, D. Ya. Spectrum and States of the BCS Hamiltonian in a Finite Domain. II. Spectra of Excitations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 53, n. 8, p. 1080–1100, 2001. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4328. Acesso em: 6 dec. 2025.