Continuous or piecewise smooth dynamical systems on 2 and 3 dimensional manifolds.
Introduction to the study of limit cycles in planar dynamical systems
Qualitative study of linear and nonlinear ordinary differential equations
Ordinary Differential Equations: qualitative theory and study of models
Qualitative theory and bifurcations of piecewise smooth vector fields
Analysis of Functional Integral Equations, Generalized Ordinary Differential Equat...