KRISTENSEN, Leif. Invariant Metrics in Coset Spaces. Mathematica Scandinavica, Berkeley, CA, United States, v. 6, p. 33–36, 1958. DOI: 10.7146/math.scand.a-10532. Disponível em: https://journals.msp.org/mscand/article/view/2809. Acesso em: 8 sep. 2026.