“…In recent years, many efficient analytical methods have been used to solve nonlinear differential equations, such as the variational iteration method [12], spreading residue harmonic balance method [13], energy balance method [14][15][16], frequency-amplitude formulation [17,18], homotopy perturbation method [19][20][21][22][23], modified harmonic balance method [24], differential quadrature method [25], parameter expansion method [26], variational approach [27,28], homotopy analysis method [29,30], higher-order Hamiltonian approach [2,[31][32][33], and so on.…”