Extremal black holes in the Hořava–Lifshitz gravity Hyung Won Lee, Yong-Wan Kim and Yun Soo Myung Eur. Phys. J. C, 68 1-2 (2010) 255-263 Published online: 29 May 2010 DOI: 10.1140/epjc/s10052-010-1344-0