Development of the theory of boundary-value problems for differential equations in the works by Oleksandr Boichuk. Neliniini Kolyvannya, [S. l.], v. 28, n. 3, p. 296–318, 2025. DOI: 10.3842/nosc.v28i3.1514 . Disponível em: https://nosc.imath.kiev.ua/index.php/nosc/article/view/1187. Acesso em: 12 apr. 2026.