  The authors give a detailed information about symmetry (Lie, non-Lie,
conditional) of nonlinear PDEs for spinor, vector and scalar fields; using
advanced methods of group-theoretical, symmetry analysis construct wide
families of classical solutions of the nonlinear Dirac, Yang-Mills,
Maxwell-Dirac, Dirac-d'Alembert, d'Alembert-Hamilton equations; expound a new
symmetry approach to variable separation in linear and nonlinear PDEs, which
allows, in particular, to classify separable Schroedinger equations.
  The book offers a uniform and relatively simple presentation of a
considerable amount of material that is otherwise not easily available. The
basic part of the book contains original results obtained by the authors. It is
sure to be of interest to mathematical and theoretical physicists, particularly
those working on classical and quantum field theories and on nonlinear
dynamical systems.
