[1] WANG M L,LI X Z,ZHANG J L.The ((G')/G)-expansion method and travelling wave solutions of nonlinear evolution equations in mathematical physics[J].Physics Letter A,2008,372(4):417.
[2] [5] MILHAILOV A V,SHABAT A B,SOKOLOV V V.Thesymmetry approach to classification of integrableequations[M]//What is integrability?Berlin:Springer Berlin Heidelberg,1991:115-184.
[3] [6] HE G L,GENG X G,WU L H.The application of trigonal curve to the Mikhailov-Shabat-Sokolov flows[J].Zeitschrift für Angewandte Mathematik und Physik,2016,67:1.