On periodic solutions of sublinear Duffing equations

Semilinear Duffing Equations Crossing Resonance Points

“…In order to prove Theorem A, we need a generalized version of the Poincare Birkhoff twist theorem due to Ding [10,11] and cited in [7]. A simple expression of the generalization of the twist theorem goes as follows.…”

Harmonic and subharmonic solutions of the SD oscillator

“…(4) has a unique harmonic solution when Loud's condition holds. After this, Ding et al [8][9][10] proved the existence of harmonic solutions for some special equations of (4) which do not satisfy Loud's condition. When a = 0, Eq.…”

Periodic solutions of sublinear Liénard differential equations

“…From then on, there have appeared many works which generalized condition (1.5) in different styles (see [2][3][4][5][6][7][8][9][10][11] and references therein). In particular, some onesided growth conditions on g(x) or G(x) (= …”