Landesman-Lazer condition for periodic problems with jumping nonlinearities.
(English).Commentationes Mathematicae Universitatis Carolinae,
vol. 28
(1987),
issue 4,
pp. 784-785
[1] R. Iannacci M. N. Nkashama: Unbounded perturbations of forced second order ordinary differential equations at resonance. J. Differential Equations 69 (1987), 289-309. MR 0903389