KADISON, R. V.; PEDERSEN, G. K. Means and convex combinations of unitary operators. MATHEMATICA SCANDINAVICA, [S. l.], v. 57, p. 249–266, 1985. DOI: 10.7146/math.scand.a-12116. Disponível em: https://www.mscand.dk/article/view/12116. Acesso em: 29 apr. 2024.