Differential Equations & Mathematica, Bill Davis and Jerry Uhl
Been a long damn time since my undergrad uni diffy-q class. This is a computer textbook, better than print in every possible way.
I think the name of the new edition is Making Math: Differential Equations.
This is useful review before I program in the Austrlian economist's models, which will certainly happen one of these years when I have some spare time.