CHERVAK, Yu. Yu. On one cut-off method for discrete problems . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 23, n. 6, p. 839–843, 1971. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8638. Acesso em: 5 dec. 2025.