GRITSANS, Armands; SADYRBAEV, Felix. Nonlinear spectra: The Neumann problem. Mathematical Modelling and Analysis, [S. l.], v. 14, n. 1, p. 33–42, 2009. DOI: 10.3846/1392-6292.2009.14.33-42. Disponível em: https://journals.vilniustech.lt/index.php/MMA/article/view/6515. Acesso em: 3 jul. 2025.