CHEREMNIKH, E.; IVASYK, H.; OLEKSIV, I. Finding the condition of finiteness of the discrete spectrum of a nonself-adjoint friedrichs model in the case of one-dimensional perturbation. Technology audit and production reserves, [S. l.], v. 4, n. 2(54), p. 46–49, 2020. DOI: 10.15587/2706-5448.2020.210775. Disponível em: https://journals.uran.ua/tarp/article/view/210775. Acesso em: 12 may. 2024.