Superluminal group velocity in an anisotropic metamaterial Hailu Luo, Wei Hu, Weixing Shu, Fei Li and Zhongzhou Ren Europhys. Lett., 74 6 (2006) 1081-1087 Published online: 12 May 2006 DOI: 10.1209/epl/i2006-10046-4