“…The geometric singular perturbation theory (GSPT) (see Fenichel [15] and Jones [20]) is an effective tool to deal with this issue (e.g. see Li et al [24][25][26], Du et al [11,13,14], Chen et al [8], Wang and Zhang [39], Qiu et al [31], Zhu et al [46], Mansour [29]). Ogawa [30] and Du et al [12] studied the so-called 'Saddle loop' case (see figure 1(a)) corresponding to the unperturbed Kortewegde Vries (KdV) equation and Nizhnik-Novikov-Veselov equation, it can be seen that the Hamiltonian system with an elliptic Hamiltonian of degree three is H(U, V) = 1 2 V 2 + f(U), where f (U) is a polynomial in U of degree three.…”