1. Theory of Ordinary Differential Equations;Coddington,1955
2. Fixed Points and Topological Degree in Nonlinear Analysis;Cronin,1964
3. Quasilinear equations and equations with large nonlinearities;Cronin;Rocky Mountain J. Math.,1974
4. Differential Equations: Stability, Oscillation, Time Lags;Halanay,1966
5. Ordinary Differential Equations;Hale,1980