Q:

Problem books in ODE

I'm studying Ordinary differential equations right now in the level of Hartman's book.
I've never seen problem books in ODE in this level even if you consider it without solutions.
I would like to know if one of you know any problem book in ODE in this level?
Thanks a lot

A:

I do not know of another book like this one.
I think you can do several things, like finding books with the main themes, for example:

Example 1: About Exponential Dichotomy of Linear Autonomous Differential Equations, Mircea Reghis
Example 2: Perturbation Methods for Differential Equations, Bhimsen Shivamoggi
Example 3: Countable Systems of Differential Equations by A. M. Samoilenko, Yu. V. Teplinskii
Another Suggestion: Review the extensive list of references in his book and see other books on the main themes that he used, including the referenced papers 

