He's variational method for the time-space fractal (3 + 1)-dimensional extended quantum Zakharov-Kuznetsov equation in plasma physicsKang-Jia Wang, Qing-Gang Xia and Guo-Dong WangEPL, 134 2 (2021) 20006DOI: https://doi.org/10.1209/0295-5075/134/20006