1. Asymptotic Behavior and Stability Problems in Ordinary Differential Equations;Cesari,1959
2. Functional analysis and periodic solutions of nonlinear differential equations;Cesari;Contr. to diffl Equat.,1962
3. Theory of Ordinary Differential Equations;Coddington,1955
4. Harmonic and subharmonic response of an on-off control system to sinusoidal inputs;Fleishman;J. Franklin Inst.,1960