1. A. Castro, A. Maloney, A. Strominger, Phys. Rev. D 82, 024008 (2010). arXiv:1004.0996 [hep-th]
2. C. Krishnan, J. High Energy Phys. 1007, 039 (2010). arXiv:1004.3537 [hep-th]
3. M. Cvetic, F. Larsen, Nucl. Phys. B 506, 107 (1997). hep-th/9706071
4. M. Cvetic, F. Larsen, J. High Energy Phys. 1202, 122 (2012). arXiv:1106.3341 [hep-th]
5. B. Chen, J. Long, Phys. Rev. D 82, 126013 (2010). arXiv:1009.1010 [hep-th]