$ $. Grigorchuk Rostislav Ivanovich — 60th anniversary. Carpathian Mathematical Publications, [S. l.], v. 5, n. 1, p. 164–165, 2013. Disponível em: https://journals.pnu.edu.ua/index.php/cmp/article/view/3666. Acesso em: 28 apr. 2024.