  The quantization method based on the quantum Hamiltonian Jacobi equation, is
extended to two-dimensional non-separable but integrable Hamiltonians. It is
shown that each wave function for those systems corresponds to a well-defined
family of classical trajectories, enveloped by a caustic. The energy
eigenvalues and the values of the wave functions on the caustic are obtained by
solving the 1-dim quantum Hamilton Jacobi equation of the caustic' arcs.
Results are in good agreement with those obtained by usual methods.
