“…The condition on nonlinear term f (·, t) at infinity, and the oddness of f globally is essential in applying this theorem. However, by employing the dual-fountain theorem, we design our main theorem when f (·, t) is carried out near zero, and f (·, t) is odd in t for a small t. Therefore, our approach for obtaining this consequence is somewhat different from former related works [8,9,24,29,38,[41][42][43][44].…”