BOTYUK, A. O. Exact solution of one boundary-value problem. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 49, n. 7, p. 998–1001, 1997. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5092. Acesso em: 5 dec. 2025.