DMYTRYSHYN, M.I. Approximation of positive operators by analytic vectors. Carpathian Mathematical Publications, [S. l.], v. 12, n. 2, p. 412–418, 2020. DOI: 10.15330/cmp.12.2.412-418. Disponível em: https://journals.pnu.edu.ua/index.php/cmp/article/view/4441. Acesso em: 17 jun. 2024.