KEHLET, Esben T. On extensions of locally compact groups and unitary groups. Mathematica Scandinavica, Berkeley, CA, United States, v. 45, p. 35–49, 1979. DOI: 10.7146/math.scand.a-11823. Disponível em: https://journals.msp.org/mscand/article/view/1821. Acesso em: 25 jul. 2026.