1. Periodic trajectories on stationary Lorentzian manifolds;Bartolo;Nonlinear Anal.,2001
2. J.K. Beem, P.E. Ehrlich, K.L. Easley, Global Lorentzian Geometry, Monographs Textbooks Pure, Applied Mathematics, Vol. 202, Dekker Inc., New York, 1996.
3. On the existence of infinitely many geodesics on space–time manifolds;Benci;Adv. Math.,1994
4. On the existence of multiple geodesics in static space–times;Benci;Ann. Inst. H. Poincaré Anal. Non Linéaire,1991
5. V. Benci, D. Fortunato, F. Giannoni, On the existence of periodic trajectories in static Lorentz manifolds with singular boundary, “Nonlinear Analysis”, a tribute in honour of G. Prodi (A. Ambrosetti–A. Marino Eds.) Quaderni Scuola Norm. Sup. Pisa (1991) 109–133.