“…In our work we obtain periodic solutions of Hamiltonian function which are perturbation of the integrable Kepler problem with 3 degrees of freedom. Our results combine the discrete symmetries of the Hamiltonian and the Continuation Poincaré method, using strongly the first approximation of the solutions of the full Hamiltonian system given by a variational system, although these ideas have been used in other works (see for example, [1], [2], [4], [9], [16], [20], [21], [22], [23], etc.) for specific perturbations or under a different point of view.…”