Newtonian, Post Newtonian and Parameterized Post Newtonian limits of
  f(R, G) gravity
  We discuss in detail the weak field limit of f(R,G) gravity taking into
account analytic functions of the Ricci scalar R and the Gauss-Bonnet invariant
G. Specifically, we develop, in metric formalism, the Newtonian, Post Newtonian
and Parameterized Post Newtonian limits starting from general f(R, G)
Lagrangian. The special cases of f(R) and f(G) gravities are considered. In the
case of the Newtonian limit of f(R, G) gravity, a general solution in terms of
Green's functions is achieved.
