Dichroism in uniaxial crystals

I need a same help with it. Some books where i can find a real math explanation of this effect will be good help!! simple exp of this effect will be good too)

Since the complex index of refraction $n+i\kappa$ contains both the speed of light transformation and the absorption transformation of a particular material, this can be generalized to a tensor valued index of refraction for any material: $${\bf{n}}_{\text{tensor}}=\begin{pmatrix}n_{00}+i\kappa_{00}&n_{01}+i\kappa_{01}&n_{02}+i\kappa_{02}\\ n_{10}+i\kappa_{10}&n_{11}+i\kappa_{11}&n_{12}+i\kappa_{12}\\ n_{20}+i\kappa_{20}&n_{21}+i\kappa_{21}&n_{22}+i\kappa_{22} \end{pmatrix}$$ so that different directions in a volumetric material have different indices of refraction. This matrix can then be diagonalized to obtain three principal indices of refraction corresponding to three (not necessarily orthogonal) principal axes (i.e. the directions along which light propagating will "see" the respective principal index of refraction).