JENSEN, Anders; JONDRUP, Soren. Smash products, group actions and group graded rings. Mathematica Scandinavica, Berkeley, CA, United States, v. 68, p. 161–170, 1991. DOI: 10.7146/math.scand.a-12353. Disponível em: https://journals.msp.org/mscand/article/view/1275. Acesso em: 24 jul. 2026.