“…This method has been used in the theoretical analysis of the Duffing oscillator [Gitterman, 2001;Blekhman & Landa, 2004], the quintic oscillator [Jeyakumari et al, 2009a;Jeyakumari et al, 2009b], the delayed system [Jeevarathinam, 2011], the friction system [Thomsen, 1999], the supported beam [Tcherniak, 1999], the ratchet system [Borromeo & Marchesoni, 2006], the fractional-order system [Yang & Zhu, 2012, etc. among others.…”