KLYUS, I. S.; PTASHNIK, B. I. A Multipoint Problem for Pseudodifferential Equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 55, n. 1, p. 22–29, 2003. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3884. Acesso em: 5 dec. 2025.