\[W_{\kappa,\mu}\left(x\right)=\sqrt{\frac{x}{X}}\*\left(\frac{2\mu^{2}-\kappa x%
+\mu X}{(\mu-\kappa)x}\right)^{\mu}\*\left(\frac{X+x-2\kappa}{2}\right)^{%
\kappa}\*e^{-\frac{1}{2}X-\kappa}\*\left(1+O\left(\frac{1}{\mu}\right)\right),\]