A NOTE ON THE CONSTRUCTION OF PROJECTION OPERATORS IN THE SEMI-CLASSICAL APPROXIMATION

PROJECTION OPERATORS IN BOSON THEORY.

APPROXIMATION METHODS IN CLASSICAL AND QUANTUM THEORIES

CLASSICAL FUNCTIONS CORRESPONDING TO QUANTUM OPERATORS.

BARRIER PENETRATION: SEMI-CLASSICAL APPROXIMATION

Green functions and projection operators in the semiclassical approximation

On the equivalence of some projection operator techniques