PETRINA, D. Ya. New second branch of the spectrum of the BCS Hamiltonian and a “pseudogap”. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 57, n. 11, p. 1508–1533, 2005. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3704. Acesso em: 27 apr. 2025.