Hochstadt Harry. Differential Equations: A Modern Approach

New York: Dover, 2012. — 316 p. — ISBN: 0486619419, 111412723XModern approach to differential equations presents subject in terms of ideas and concepts rather than special cases and tricks which traditional courses emphasized. No prerequisites needed other than a good calculus course. Certain concepts from linear algebra used throughout. Problem section at end of each chapter. 134 problems.