1. V.B. Andreev, N.B. Kopteva, On the investigation of difference schemes with a central approximation of the first order derivative, Zh. Vychisl. Mat. i Mat. Fiz. 36(8) (1996) 101–117 (in Russian).
2. N.S. Bakhvalov, Towards optimization of methods for solving boundary value problems in the presence of boundary layers, Zh. Vychesl. Mat. i Mat. Fiz. 9 (1969) 841–859 (in Russian).
3. Differentiability properties of solutions of the equation −ε2Δ u+ru=f(x,y) in a square.;Han;SIAM J. Math. Anal.,1990
4. Analysis of some difference approximations for a singular perturbation problem without turning points;Kellogg;Math. Comput.,1978
5. A hybrid difference scheme on a Shishkin mesh for linear convection–diffusion problems;Linß;Appl. Numer. Math.,1999