PetrinaD. Ya. “Spectrum and States of the BCS Hamiltonian in a Finite Domain. III. BCS Hamiltonian With Mean-Field Interaction”. Ukrains’kyi Matematychnyi Zhurnal 54, no. 11 (November 25, 2002): 1486-1505. Accessed November 22, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4187.