SCHLICHTKRULL, Henrik. One-dimensional $K$-types in finite dimensional representations of semisimple Lie groups: A generalization of Helgason’s theorem. Mathematica Scandinavica, Berkeley, CA, United States, v. 54, p. 279–294, 1984. DOI: 10.7146/math.scand.a-12059. Disponível em: https://journals.msp.org/mscand/article/view/1568. Acesso em: 25 jul. 2026.