VOLKOVA, M. G.; TARASENKO, A. A. About one class of Hilbert space uncoditional bases. Methods of Functional Analysis and Topology, [S. l.], v. 13, n. 3, p. 296–300, 2007. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/357. Acesso em: 16 dec. 2025.