FAM KI AN. Concerning two approximate methods for solution of the Neumann nonlinear problems . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 40, n. 5, p. 619–625, 1988. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8810. Acesso em: 6 dec. 2025.