1. Alternative methods in nonlinear analysis;Cesari, Lamberto,1975
2. Nonlinear oscillations in the frame of alternative methods;Cesari, Lamberto,1976
3. \bysame, Functional analysis and nonlinear differential equations, Dynamical Systems (Cesari, Kannan and Schuur, editors), Dekker, New York, 1976.
4. An abstract existence theorem across a point of resonance;Cesari, Lamberto,1977
5. Nonlinear oscillations across a point of resonance for nonselfadjoint systems;Cesari, Lamberto;J. Differential Equations,1978