References

1: C. M. Bender and S. A. Orszag, Advanced Mathematical Methods for Scientists and Engineers, McGraw-Hill, 1978.
2: G. Birkhoff and G.-C. Rota, Ordinary Differential Equations, 3rd ed., Wiley, New York, 1978.
3: J. H. Hubbard, What it means to understand a differential equation, College Mathematics Journal 25:5 (1994), 372--384.
4: J. H. Hubbard and B. H. West, Differential Equations: A Dynamical Systems Approach, Springer-Verlag, New York, 1991.
5: D. Zwillinger, Handbook of Differential Equations, Academic Press, New York, 1989, pp. 284--286.