  Spin coherent states play a crucial role in defining QESM (quasi-exactly
solvable models) establishing a strict correspondence between energy spectra of
spin systems and low-lying quantum states for a particle moving in a potential
field of a certain form. Spin coherent states are also used for finding the
Wigner-Kirkwood expansion and quantum corrections to energy quantization rules.
The closed equation which governs dynamics of a quantum system is obtained in
the spin coherent representation directly for observable quantities.
