Derivation of Non-isotropic Phase Equations from a General   Reaction-Diffusion Equation
  A non-isotropic version of phase equations such as the Burgers equation, the K-dV-Burgers equation, the Kuramoto-Sivashinsky equation and the Benney equation in the three-dimensional space is systematically derived from a general reaction-diffusion system by means of the renormalization group method. 
Y.Masutomi and K. Nozaki