Canonical and Functional Schrodinger Quantization of Two--Dimensional   Dilaton Gravity
  We discuss the relation between canonical and Schrodinger quantization of the CGHS model. We also discuss the situation when background charges are added to cancel the Virasoro anomaly. New physical states are found when the square of the background charges vanishes. 
S. Cassemiro F. F. and Victor O. Rivelles