This three-part graduate-level treatment begins with classical perturbation techniques, discussing the Lagrange expansion theorem, matrix exponential, invariant imbedding, and dynamic programming. The second part concentrates on equations, presenting renormalization techniques of Lindstedt and Shohat and averaging techniques by Bellman and Richardson. The concluding chapter focuses on second-order linear differential equations, illustrating applications of the WKB-Liouville method and asymptotic series. Exercises, comments, and an annotated bibliography follow each demonstration of technique. A course in intermediate calculus and a basic understanding of ordinary differential equations are prerequisites. 1966 ed. 7 figures.