GREEN, W. L.; MORLEY, T. D. Operator means, fixed points, and the norm convergence of monotone approximants. MATHEMATICA SCANDINAVICA, [S. l.], v. 60, p. 202–218, 1987. DOI: 10.7146/math.scand.a-12180. Disponível em: https://www.mscand.dk/article/view/12180. Acesso em: 3 may. 2024.