GRANIRER, E. Extremely Amenable Semigroups. Mathematica Scandinavica, Berkeley, CA, United States, v. 17, p. 177–197, 1965. DOI: 10.7146/math.scand.a-10772. Disponível em: https://journals.msp.org/mscand/article/view/2552. Acesso em: 25 jul. 2026.