ŠTIKONAS, Artūras; ŠTIKONIENĖ, Olga. Characteristic functions for sturm—liouville problems with nonlocal boundary conditions. Mathematical Modelling and Analysis, [S. l.], v. 14, n. 2, p. 229–246, 2009. DOI: 10.3846/1392-6292.2009.14.229-246. Disponível em: https://journals.vilniustech.lt/index.php/MMA/article/view/6543. Acesso em: 3 jul. 2025.