KOWYNIA, Joanna. The unicity of best approximation in a space of compact operators. Mathematica Scandinavica, Berkeley, CA, United States, v. 108, n. 1, p. 146–160, 2011. DOI: 10.7146/math.scand.a-15164. Disponível em: https://journals.msp.org/mscand/article/view/533. Acesso em: 24 jul. 2026.