HELGASON, Sigurdur. Some Remarks on the Exponential Mapping for an Affine Connection. Mathematica Scandinavica, Berkeley, CA, United States, v. 9, p. 129–146, 1961. DOI: 10.7146/math.scand.a-10631. Disponível em: https://journals.msp.org/mscand/article/view/2714. Acesso em: 25 jul. 2026.