Integrability, solitons, periodic and travelling waves of a generalized (3+1)-dimensional variable-coefficient nonlinear-wave equation in liquid with gas bubblesGao-Fu Deng and Yi-Tian GaoEur. Phys. J. Plus, 132 6 (2017) 255DOI: https://doi.org/10.1140/epjp/i2017-11515-8