Anyone know a good reference for the asymptotic study of integrals of the form $\int_{\Gamma}f(s)e^{ng(s)}ds$ , $n\to\infty$, where $f(z)$ and $g(z)$ are analytic functions in the domain containing the contour $\Gamma$?. The books I have consulted only refer to the case where $g(z)$ has critical points and that study reduces to the method of Laplace or Waltson's lemma. But, i need to study the case where $g(z)$ has no critical points.
Thank you all for your help!