Discrete multipole dark solitons in saturable nonlinearity media with parity-time symmetric latticesZhiwei Shi, Jing Xue, Zhu Xing, Yang Li and Huagang LiEur. Phys. J. Plus, 132 2 (2017) 79DOI: https://doi.org/10.1140/epjp/i2017-11348-5