Mak and T. Harko, Int. J. Mod. Phys. [**D9**]{}, 97 (2000); Aust. J. Phys. [**53**]{}, 241 (2000); Int. J. Mod. Phys. [**D9**]{}, 475 (2000). R. Maartens and J. Triginer, Phys. Rev. [**D56**]{}, 4640 (1997). A. A. Coley and R. J. van den Hoogen, Class. Quantum Grav. [**12**]{}, 1977 (1995) ; A. A. Coley and R. J. van den Hoogen, Phys. Rev. [**D54**]{}, 1393 (1996) ; A. Di Prisco, L. Herrera and J. Ibanez, Phys. Rev. [**D63**]{}, 023501 (2001). Abdussatar and R. G. Vishwakarma, Class. Quantum Grav. [**14**]{}, 945 (1997).

A. I. Arbab and A. Beesham, Gen. Rel. Grav. [**32**]{}, 615 (2000).

C. M. Chen, T. Harko, and M. K. Mak, Phys. Rev. [**D64**]{}, 124017 (2001); T. Harko and M. K. Mak, Class. Quant. Grav. [**20**]{}, 407 (2003). J. A. Belinchon, T. Harko, and M. K. Mak, Class. Quant. Grav. [**19**]{}, 3003 (2002). C. S. J. Pun, L. A. Gergely, M. K. Mak, Z. Kovacs, G. M. Szabo, and T. Harko, Phys.Rev. [**D77**]{}, 063528 (2008).

BRAHMS Collaboration, I. Arsene [*et al.*]{}, Nucl. Phys. A [**757**]{}, 1 (2005). PHOBOS Collaboration, B. B. Back [*et al.*]{}, Nucl. Phys. A [**757**]{}, 28 (2005). PHENIX Collaboration, K. Adcox [*et al.*]{}, Nucl. Phys. A [**757**]{} (2005) 