1. Perturbation Techniques in Mathematics, Physics and Engineering;Bellman,1964
2. Perturbation Methods in Applied Mathematics;Cole,1968
3. Introduction to Singular Perturbation;O'Malley,1974
4. Perturbation Methods;Nayfeh,1973
5. Perturbation Methods in Fluid Mechanics, Annotated Edition;Van Dyke,1975