BOTYUK, A. O. Quasilinear periodic boundary-value problem. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 49, n. 12, p. 1690–1693, 1997. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5174. Acesso em: 5 dec. 2025.