Constraining anisotropy of the universe from different groups of type-Ia supernovae Zhe Chang, Xin Li, Hai-Nan Lin and Sai Wang Eur. Phys. J. C, 74 3 (2014) 2821 Published online: 27 March 2014 DOI: 10.1140/epjc/s10052-014-2821-7