ZVEREVA, M. B.; POKORNYI, Yu. V.; SHABROV, S. A. On extension of the Sturm-Liouville oscillation theory to problems with pulse parameters. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 60, n. 1, p. 95–99, 2008. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3140. Acesso em: 7 apr. 2025.