HILDEBRANDT, S.; KAUL, H.; WIDMAN, K.- 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: 4 may. 2024.