“…Recently, many authors (Khan a new analytical approximation by variational iterative method (VIM); but the solution contains many harmonic terms. Many analytical techniques (Hosen et al, 2012;Mickens, 1996Mickens, , 2001Lim and Wu, 2003;Tiwari et al, 2005;Ozis and Yildirim, 2007;Ghadimi and Kaliji, 2013;Ganji et al, 2009;Zhao, 2009;Akbarzade and Farshidianfar, 2014;Khan et al, 2013a,b) have been used to solve strongly nonlinear oscillator systems having a rational force (such as Duffingharmonic oscillator: €…”