Positive solutions of neutral delay differential equation. Péics, Hajnalka; Karsai, János — 2002 Novi Sad Journal of Mathematics
On properties of nonlinear second-order systems under nonlinear impulse perturbations. Graef, John R.; Karsai, János — 1997 Electronic Journal of Differential Equations (EJDE) [electronic only]
On the oscillation of impulsively damped halflinear oscillators. Graef, John R.; Karsai, János — 2000 Electronic Journal of Qualitative Theory of Differential Equations [electronic only]