1. AXELSSON O., Stability and error estimates of Galerkin finite element approximations for convection-diffusion equations, I.M.A. Journal Num. Anal., 1 (1981), 329-3456413130508.76069
2. AXELSSON O., On the numerical solution of convection dominated convection-diffusion problems, in : Proc. Tagung Math. Physik, Karl-Marx-Stadt 1983,Teubner-Texte, Leipzig 1984.7817520563.76084
3. BARDOS C., RAUCH J., Maximal positive boundary value problems as limits of singular perturbations problems, Transact. Amer. Math. Soc, 270 (1982) 2,377-400.6453220485.35010
4. DEVINATZ A., ELLIS R., FRIEDMAN A. , The asymptotic behaviour of the first real eigenvalue of second order elliptic operators with a small parameter in the highest derivatives II. Indiana Univ. Math. J., 23 (1974), 991-1011.3447090263.35026
5. FELGENHAUER A., Application of a generalized maximum principle to estimate the corner layers in the n-dimensional case, in : Singularly perturbed differential equations and applications (J. Förste ed.), Akademie der Wissenschaften der DDR, Inst. f. Math., Report R-Mech 03/84, Berlin 1984, 1-8.