HILDEBRANDT, Stefan; KAUL, Helmut; WIDMAN, Kjell-ove. Harmonic mappings into Riemannian manifolds with non-positive sectional curvature. MATHEMATICA SCANDINAVICA, [S. l.], v. 37, p. 257–263, 1975. DOI: 10.7146/math.scand.a-11604. Disponível em: https://www.mscand.dk/article/view/11604. Acesso em: 5 dec. 2025.