On step-like contrast structure of singularly perturbed systems. Ni, Mingkang; Wang, Zhiming — 2009 Boundary Value Problems [electronic only]
On the step-type contrast structure of a second-order semilinear differential equation with integral boundary conditions. Xie, Feng; Jin, Zhaoyang; Ni, Mingkang — 2010 Electronic Journal of Qualitative Theory of Differential Equations [electronic only]