}   \dot x=f(x)+{\varepsilon}g(t,x,{\varepsilon}).$$ where $f\in C^0({{\mathbb{R}}}^n, {{\mathbb{R}}}^n), g\in C^0({{\mathbb{R}}}\times {{\mathbb{R}}}^n \times [0,0], {{\mathbb{R}}}^n)$ is $T$-periodic and ${\varepsilon}>0$ is 