TEPNADZE, T. On the approximation properties of Cesàro means of negative order of double Vilenkin – Fourier series. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 72, n. 3, p. 391–406, 2020. DOI: 10.37863/umzh.v72i3.6045. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/6045. Acesso em: 5 dec. 2025.