STASYUK, S. A. Best $m$-term trigonometric approximation for periodic functions with low mixed smoothness from the Nikol’skii – Besov-type classes. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 68, n. 7, p. 983–1003, 2016. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1896. Acesso em: 6 dec. 2025.