WONG, James C. S. Characterisations of extremly amenable semigroups. Mathematica Scandinavica, Berkeley, CA, United States, v. 48, p. 101–108, 1981. DOI: 10.7146/math.scand.a-11903. Disponível em: https://journals.msp.org/mscand/article/view/1724. Acesso em: 25 jul. 2026.