1. For a nice review, see, e.g., Deruelle, N., Madore, J.: “On the quasi-linearity of the Einstein- ‘Gauss-Bonnet’ gravity field equations” [arXiv:gr-qc/0305004]
2. Nojiri, S., Odintsov, S.D.: JHEP 0007, 049 (2000) [arXiv:hep-th/0006232]; Nojiri, S., Odintsov, S.D., Ogushi, S.: Phys. Rev. D 65, 023521 (2002) [arXiv:hep-th/0108172]
3. Kim, J.E., Kyae, B., Lee, H.M.: Nucl. Phys. B 582, 296 (2000) [Erratum-ibid. B 591, 587 (2000)] [arXiv:hep-th/0004005]; Kim, J.E., Lee, H.M.: Nucl. Phys. B 602, 346 (2001) [Erratum-ibid. B 619, 763 (2001)] [arXiv:hep-th/0010093]; Meissner, K.A., Olechowski, M.: Phys. Rev. D 65, 064017 (2002) [arXiv:hep-th/0106203]; Cho, Y.M., Neupane, I.P., Wesson, P.S.: Nucl. Phys. B 621, 388 (2002) [arXiv:hep-th/0104227]; Neupane, I.P.: Class. Quant. Grav. 19, 5507 (2002) [arXiv:hep-th/0106100]; Cho, Y.M., Neupane, I.P.: Int. J. Mod. Phys. A 18, 2703 (2003) [arXiv:hep-th/0112227]; Gregory, J.P., Padilla, A.: Class. Quant. Grav. 20, 4221 (2003) [arXiv:hep-th/0304250]; Charmousis, C., Davis, S.C., Dufaux, J.F.: JHEP 0312, 029 (2003) [arXiv:hep-th/0309083]
4. Deruelle, N., Sasaki, M.: Prog. Theor. Phys. 110, 441 (2003) [arXiv:gr-qc/0306032]
5. Neupane, I.P.: Phys. Lett. B 512, 137 (2001) [arXiv:hep-th/0104226]