Regularization of an Ill-posed Cauchy Problem for the Wave Equation   (Fourier Method)
  An ill-posed Cauchy problem for the wave equation is considered: the solution is to be determined by the Cauchy data on some part of the time-space boundary. By means of Fourier method we obtain a regularization algorithm for this problem, which is given by rather explicit formula. 
M.N. Demchenko
math.AP