Solitons, breathers and rogue waves for a sixth-order variable-coefficient nonlinear Schrödinger equation in an ocean or optical fiberShu-Liang Jia, Yi-Tian Gao, Chen Zhao, Zhong-Zhou Lan and Yu-Jie FengEur. Phys. J. Plus, 132 1 (2017) 34DOI: https://doi.org/10.1140/epjp/i2017-11318-y