  We approximate given potentials by means of the specially introduced
reference potentials. On the one hand their parameters may be easily found from
the usual WKB integral for the given potential; on the other hand they allow a
simple determination of the first correction to the usual quantization
condition.
  Such reference potentials are introduced in special variables as some Pade
approximants which lead usually to a very good results for various problems.
  Thus we raise the accuracy of the WKB method for a broad set of potentials
without cumbersome calculations. Higher order corrections as well as the exact
condition is also considered.
