PTASHNIK, B. I.; SYMOTYUK, M. M. Multipoint Problem with Multiple Nodes for Partial Differential Equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 55, n. 3, p. 400–413, 2003. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3914. Acesso em: 6 dec. 2025.