HAJJEJ, Z. A note on the necessity of filtering mechanism for polynomial observability of time-discrete wave equation. Carpathian Mathematical Publications, [S. l.], v. 9, n. 1, p. 98–103, 2017. DOI: 10.15330/cmp.9.1.98-103. Disponível em: https://journals.pnu.edu.ua/index.php/cmp/article/view/1452. Acesso em: 3 may. 2024.