Topological Static Spherically Symmetric vacuum Solutions in $\mathcal   F(R,G)$ Gravity
  The Lagrangian derivation of the Equations of Motion for topological static spherically symmetric metrics in $\mathcal F (R,G)$-modified gravity is presented and the related solutions are discussed. In particular, a new topological solution for the model $\mathcal F (R,G)=R+\sqrt{G}$ is found. The black hole solutions and the First Law of thermodynamic are analyzed. Furthermore, the coupling with electromagnetic field is also considered and a Maxwell solution is derived. 
Ratbay Myrzakulov, Lorenzo Sebastiani and Sergio Zerbini
gr-qc