PETRINA, D. Ya. Spectrum and states of the bcs hamiltonian in a finite domain. I. Spectrum. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 52, n. 5, p. 667–689, 2000. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4461. Acesso em: 6 dec. 2025.