“…On one side, semi-analytic methods like: generalized homotopy method (GHM) (Vazquez-Leal 2013 ), homotopy perturbation method (Araghi and Rezapour 2011 ; Araghi and Sotoodeh 2012 ; Bayat et al 2013 , 2014 ; Biazar and Eslami 2011 ; Biazar and Ghanbari 2012 ; Filobello-Nino et al 2012a , 2012b ; He 1999 , 2009 ; Khan et al 2012a , 2012b ; Vazquez-Leal 2012 ; Vazquez-Leal et al 2012a , 2012b , 2012d ), homotopy analysis method (Hassana and El-Tawil 2011 ; He 2004 ; Rashidi et al 2012a , 2012b ; Tan and Abbasbandy 2008 ), variational iteration method (Abbasbandy 2007 ; Chang 2010 ; Khan et al 2012c ), among others (Khan et al 2012d ), need an initial approximation for the sought solutions and the calculus of one or several adjustment parameters. If the initial approximation is properly chosen, the results can be highly accurate, nonetheless, there is not a general method to choose such initial approximation.…”