1. E.P. Verlinde,
arXiv:1001.0785
[hep-th]
2. F.W. Shu, Y. Gong,
arXiv:1001.3237
[gr-qc]
3. T. Padmanabhan,
arXiv:1001.3380
[gr-qc]
4. R.G. Cai, L.M. Cao, N. Ohta, Phys. Rev. D 81, 061501 (2010).
arXiv:1001.3470
[hep-th]
5. L. Smolin,
arXiv:1001.3668
[gr-qc]