NAMIOKA, I. Folner’s Conditions for Amenable Semi-Groups. MATHEMATICA SCANDINAVICA, [S. l.], v. 15, p. 18–28, 1964. DOI: 10.7146/math.scand.a-10723. Disponível em: https://tidsskrift.dk/math/article/view/10723. Acesso em: 14 aug. 2026.