1. Absolute Stability of Regulator Systems;Aizerman,1964
2. Theory of Ordinary Differential Equations;Coddington,1955
3. Fixed Points and Topological Degree in Nonlinear Analysis;Cronin,1964
4. Suppression of oscillations in nonlinear systems;Cronin,1975
5. Periodic solutions in n-dimensions and Volterra equations;Cronin;J. Differential Equations,1975