Hi everybody! Currently i'm working on 3-dimensional diffusion models using finite element method (FEM). I am familiar with the basic diffusion theory; i mean constant diffusion coefficients, diffusion-reaction problems, numerical methods (from Crank-Nicolson to FEM), isotropic materials, etc. However, i want to consider non isotropic materials and a more realistic approach of the diffusion problem in confined geometry.... Does anybody knows the basic literature about this topic?? Any help would be great. Thanks a lot.