1. Akivis, M.A., Goldberg, V.V., Lychagin, V.V.: Linearizability of d-webs, d≥4, on two-dimensional manifolds. Selecta Math. 10(4), 431–451 (2004). MR2134451 In the bibliography we will use the following abbreviations for the review journals: JFM for Jahrbuch für die Fortschritte der Mathematik, MR for Mathematical Reviews, and Zbl for Zentralblatt für Mathematik. (2006j:53019); Zbl 1073:53021
2. Beltrami, E.: Risoluzione del problema: “Riportari i punti di una superficie sopra un piano in modo che le linee geodetiche vengano rappresentate da linee rette”. Ann. Mat. Ser. I 7, 185–204 (1865); see also Opere matematiche di Eugenio Beltrami, Pubblicate per cura della Facoltà di Scienze della R. Universita di Roma. Tomo primo. Con ritratto e biografia dell’ autore. U. Hoepli, Milano, 4° (1902), vol. I, Milano, 1902, 262–280. JFM 33, p. 34
3. Chakmazyan, A.V.: Geodesic three-webs on a two-dimensional affinely connected space. Akad. Nauk Armyan. SSR Dokl. 59, 136–140 (1974) (Russian). MR0375114 (51 #11310)
4. Furness, P.M.D.: Locally symmetric structures on surfaces. Bull. Lond. Math. Soc. 80, 44–48 (1976). MR0405289 (53 #9083); Zbl 326:53041
5. Goldberg, V.V., Lychagin, V.V.: On the Blaschke conjecture for 3-webs. J. Geom. Anal. 16(1), 69–115 (2006). MR2211333 (2007b:53026); Zbl 1102:53051