BRATTSTRÖM, Gudrun. On $p$-groups as Galois groups. Mathematica Scandinavica, Berkeley, CA, United States, v. 65, p. 165–174, 1989. DOI: 10.7146/math.scand.a-12276. Disponível em: https://journals.msp.org/mscand/article/view/1371. Acesso em: 24 jul. 2026.