Schaum's Outline of Differential Equations, Fifth Edition (Schaum's Outlines)

This is the way to go to study ordinary differential equations (with 2 chapters on partial differential equation). There were many points presented confusingly in the Zill textbook which this presentation cleared right up. Differential equations is a subject that becomes clear through extensive practice of problems, so the Schaum's approach of showing many examples is ideal for this material. Strong recommend.