“…To overcome the shortcomings, many techniques have appeared in open literature, for example, parameterexpanding method [1][2][3], variational iteration method [4][5][6][7], energy balance method [8][9][10][11][12][13][14], variational approach method [15][16][17][18][19], amplitude-frequency formulation [20][21][22], homotopy perturbation method [23][24][25][26][27][28][29], and the other analytical approximate solutions [30].…”