ELLIOTT, G. A.; HANDELMAN, D. E. Extending traces to factorial traces. MATHEMATICA SCANDINAVICA, [S. l.], v. 49, p. 95–98, 1981. DOI: 10.7146/math.scand.a-11923. Disponível em: https://www.mscand.dk/article/view/11923. Acesso em: 3 may. 2024.