“…It is well known that in system (8) three codimension one bifurcation curves emanate from (β 1 , β 2 ) = (0, 0): a saddle-node, a Hopf, and a saddle-homoclinic bifurcation curve. By using either the regular perturbation or the Lindstedt-Poincaré method, an approximation to the homoclinic bifurcation curve and the corresponding solution can, theoretically, be obtained up to any order in the singular-rescaling parameter , see [40,41,1,2].…”