GRITSANS, Armands; SADYRBAEV, Felix. Two-parameter nonlinear oscillations: the neumann problem. Mathematical Modelling and Analysis, [S. l.], v. 16, n. 1, p. 23–38, 2011. DOI: 10.3846/13926292.2011.559449. Disponível em: https://journals.vilniustech.lt/index.php/MMA/article/view/5504. Acesso em: 9 may. 2025.