Semiclassical Approach & Langer's Modification of Quantization Rules

[funduk89]

Can you advise books about semiclassical approach and corrects in rule of quantization.
I mean $$\int(p)$$=$$n_{r}$$+$$\gamma$$

where $$\gamma$$ is correct are depended from boundary condition. In basic cases correct is 1/2.

 

[DrDu]

This article by Berry and Mount is the classic:

Berry MV, Mount KE. Semiclassical approximations in wave mechanics. Rep. Prog. Phys. 1972 1;35(1):315-397.