HOARE, A. H. M. Nielsen methods in groups with a length function. Mathematica Scandinavica, Berkeley, CA, United States, v. 48, p. 153–164, 1981. DOI: 10.7146/math.scand.a-11908. Disponível em: https://journals.msp.org/mscand/article/view/1723. Acesso em: 25 jul. 2026.