QCD sum rule study of hidden-charm pentaquarks Hua-Xing Chen, Er-Liang Cui, Wei Chen, Xiang Liu, T. G. Steele and Shi-Lin Zhu Eur. Phys. J. C, 76 10 (2016) 572 Published online: 24 October 2016 DOI: 10.1140/epjc/s10052-016-4438-5