@article {garrione2011resonance,
	title = {Resonance and Landesman-Lazer conditions for first order systems in R^2},
	journal = {Le Matematiche},
	volume = {66},
	number = {1},
	year = {2011},
	pages = {153{\textendash}160},
	abstract = {<p>The first part of the paper surveys the concept of resonance for $T$-periodic nonlinear problems. In the second part, some new results about existence conditions for nonlinear planar systems are presented. In particular, the Landesman-Lazer conditions are generalized to systems in $\mathbbR^2$ where the nonlinearity interacts with two resonant Hamiltonians. Such results apply to second order equations, generalizing previous theorems by Fabry [4] (for the undamped case), and Frederickson-Lazer [9] (for the case with friction). The results have been obtained with A. Fonda, and have been published in [8].</p>},
	author = {Maurizio Garrione}
}
