1. Perturbation Methods, Wiley, New York, 1973.
2. Perturbation Methods in Fluid Mechanics, Parabolic Press, Stanford, 1975.
3. and , Perturbation Methods in Applied Mathematics, Springer Verlag New York, 1981.
4. Asymptotic Analysis of Singular Perturbations, North-Holland, Amsterdam, 1979.
5. and (eds.), Numerical Analysis of Singular Perturbation Problems, Academic Press, London, 1979.