chapter 1 Introduction -- chapter 2 Boundary value problems for elliptic reaction-diffusion equations in domains with smooth boundaries -- chapter 3 Boundary value problems for elliptic reaction-diffusion equations in domains with piecewise-smooth boundaries -- chapter 4 Generalizations for elliptic reaction-diffusion equations -- chapter 5 Parabolic reaction-diffusion equations -- chapter 6 Elliptic convection-diffusion equations -- chapter 7 Parabolic convection-diffusion equations -- chapter 8 Grid approximations of parabolic reaction-diffusion equations with three perturbation parameters -- chapter 9 Application of widths for construction of difference schemes for problems with moving boundary layers -- chapter 10 High-order accurate numerical methods for singularly perturbed problems -- chapter 11 A finite difference scheme on a priori adapted grids for a singularly perturbed parabolic convection-diffusion equation -- chapter 12 On conditioning of difference schemes and their matrices for singularly perturbed problems -- chapter 13 Approximation of systems of singularly perturbed elliptic reaction-diffusion equations with two parameters -- chapter 14 Survey.