Modern Elementary Differential Equations: Second Edition

I am reminded of how good Bellman's book is by not having it with me right now......... My copy is in another continent, and the Univ São Paulo library is closed Sundays. And the full text is not online. So I have to wait. That gives me more time to appreciate Bellman's book - and the work habits of North American librarians as well. Together with Arnold's Ordinary Differential Equations, one of the must-have books on the subject. Every decent text has the dry facts. But keep copies of Bellman and Arnold handy to really understand the concepts, and to be able to do creative work using them.