The Invariance and Conservation Laws of fourth-order Difference   Equations
  We consider difference equations of order four and determine the one parameter Lie group of transformations (Lie symmetries) that leave them invariant. We introduce a technique for finding their first integrals and discuss the association between the symmetries and first integrals as well as the notion of multipliers (related to conservation laws) for difference equations. 
Mensah Folly-Gbetoula and Abdul Kara
math.CA