1868 On the hypotheses which lie at the foundation of geometry, traducido por W.K.Clifford, Nature 8 1873 183 - reimpreso en Clifford's Collected Mathematical Papers, Londres 1882 (MacMillan); Nueva York 1968 (Chelsea) http://www.emis.de/classics/Riemann/. También en Ewald, William B., ed., 1996 "From Kant to Hilbert: A Source Book in the Foundations of Mathematics", 2 vols. Oxford Uni. Press: 652–61.