1. Cheng WF, Temam R, Wang X. New algorithms for a class of PDE displaying boundary layer behavior. Dedicated to Cathleen Morawetz on the occasion of her 75th birthday. Meth Appl Anal 2000;7(2):363–90
2. Singular perturbation;Erdelyi;Bull Am Math Soc,1962
3. The mathematical structure of the boundary layer problem;Friedrichs,1941
4. Introduction to perturbation methods;Holmes,1995
5. Matched asymptotics expansion, ideas and techniques;Lagerström,1988