KHOMA, N. H.; TSYNALKO, P. V. Smooth solution of one boundary-value problem. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 49, n. 12, p. 1712–1716, 1997. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5178. Acesso em: 14 apr. 2025.