The generalized cosmic equation of state: a revised study with cosmological standard rulers Yubo Ma, Jia Zhang, Shuo Cao, Xiaogang Zheng, Tengpeng Xu and Jingzhao Qi Eur. Phys. J. C, 77 12 (2017) 891 Published online: 20 December 2017 DOI: 10.1140/epjc/s10052-017-5461-x