Formal structure and classification of theories of oriented materials

Recent theories of Oriented materials have been devised to serve an amazing variety of applications; to quote only the most widely pursued and the most succesful ones:wave propagation in the presence of dispersion effects; diffusion of dislocations in crystal lattices; flow of anisotropic fluids, of granular media and of suspensions in fluids. These theories are motivated by a number of models of differing subtlety and varying nature, such as MINDLIN's "unit cell", ERICKSEN's "collection of microelements" or RIVLIN's "particle" consisting of mass-points.