1. On the existence of infinitely many trajectories for a class of static Lorentzian manifolds like Schwarzschild and Reissner–Nordström space-times;Bartolo;J. Math. Anal. Appl.,1996
2. V. Benci, D. Fortunato, Periodic trajectories for the Lorentz metric of a static gravitational field, in: H. Beresticki, I. Ekeland, M. Coron (Eds.), Proc. Variational Problems, Paris, 1988.
3. On the existence of multiple geodesics in static space-times;Benci;Ann. Inst. Henri Poincaré, Anal. Nonlinéaire,1991
4. V. Benci, D. Fortunato, F. Giannoni, On the existence of periodic trajectories in static Lorentz manifolds with nonsmooth boundary, in: A. Ambrosetti, A. Marino (Eds.), Nonlinear Analysis, a Tribute in honour of G. Prodi, Quaderni della Scuola Normale Superiore, Pisa, 1991, pp. 109–133.
5. On the existence of closed geodesics on noncompact Riemannian manifolds;Benci;Duke Math. J.,1992