The 12-th Scientific Session of the Mathematical Commission of the T. H. Shevchenko Scientific Society. Neliniini Kolyvannya, [S. l.], v. 4, n. 3, p. 432–432, 2001. Disponível em: https://nosc.imath.kiev.ua/index.php/nosc/article/view/186. Acesso em: 12 apr. 2026.