SMIRNOV, Sergey. A geometrical criterion for nonexistence of constant-sign solutions for some third-order two-point boundary value problems. Nonlinear Analysis: Modelling and Control, [S. l.], v. 25, n. 3, p. 502–508, 2020. DOI: 10.15388/namc.2020.25.16776. Disponível em: https://www.journals.vu.lt/nonlinear-analysis/article/view/16776.. Acesso em: 18 jul. 2024.