1. Álvarez, J.C. The Symplectic Geometry of Spaces of Geodesics. Ph.D. Thesis, Rutgers University, 1995.
2. Álvarez, J.C. A Symplectic Construction of Desarguesian Metrics on R n. Preprint.
3. Àlvarez, J.C., Gelfand, I.M., Smirnov, M. Crofton Densities, Symplectic Geometry, and Hilbert’s Fourth Problem. In preparation.
4. Busemann, H. Geometries in which Planes Minimize Area. Annali Mat. Pure Appl. (IV) 55, 1961.
5. Gelfand, I.M., Gindikin, S.G., Graev, M.I. Integral Geometry in Affine and Projective Spaces. Journal of Soviet Mathematics, 1982.