ANDRIENKO, V. A. On the order of growth of rectangular partial sums of double orthogonal series. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 51, n. 10, p. 1299–1310, 1999. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4728. Acesso em: 14 apr. 2025.