PEČIULYTĖ, S.; ŠTIKONIENĖ, O.; ŠTIKONAS, A. Investigation of Negative Critical Points of the Characteristic Function for Problems with Nonlocal Boundary Conditions. Nonlinear Analysis: Modelling and Control, [S. l.], v. 13, n. 4, p. 467–490, 2008. DOI: 10.15388/NA.2008.13.4.14552. Disponível em: https://www.zurnalai.vu.lt/nonlinear-analysis/article/view/14552. Acesso em: 8 jul. 2025.