1. Periodic solutions in the large of nonlinear ordinary differential equations;Cesari;Rend. Mat.,1975
2. Perturbations of Liénard systems with symmetries;Bowman,1977
3. Existence theorems for periodic solutions of nonlinear Lipschitzian differential systems and fixed point theorems;Cesari;Contributions to the Theory of Nonlinear Oscillations,1960
4. Alternative methods in nonlinear analysis;Cesari;International Conference on Differential Equations,1974
5. Solutions in the large of Liénard systems with forcing terms;Cesari;Annali Mat. pura appl.,1976