Hilbert space frames, Riesz bases and tensor sums. Gulf Journal of Mathematics, [S. l.], v. 2, n. 3, 2014. DOI: 10.56947/gjom.v2i3.232. Disponível em: https://www.gjom.org/index.php/gjom/article/view/232. Acesso em: 20 aug. 2026.