1. An Introduction to Phase-Integral Methods;Heading,1962
2. Perturbation Methods in Fluid Mechanics;Van Dyke,1964
3. Perturbation Methods in Applied Mathematics;Cole,1968
4. Matched Asymptotic Expansions and Singular Perturbations;Eckhaus,1973
5. Introduction to Singular Perturbation;O'Malley,1974