BETIUK-PILARSKA, Anna; PRUS, Stanisław. Uniform nonsquareness of direct sums of Banach spaces. Topological Methods in Nonlinear Analysis, [S. l.], v. 36, n. 1, p. 181–186, 2009. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2009.036. Acesso em: 8 jul. 2025.