Integral over Green's function of wave equation

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the following paper says if $f(\vec{x})=f(x)$ does only depend on $x$ then we have

$\int d^3x' \frac{e^{\pm ik_{\phi}|\vec{x}-\vec{x}'|}}{|\vec{x}-\vec{x}'|} f(\vec{x}')= \frac{2\pi i}{k_{\phi}} e^{ ik_{\phi}x} \int dx' e^{-ik_{\phi}x'}f(x')$

You can find this by going from (3) to (4) in the linked paper. Further reduced this means that one can integrate out the two dimensional integral and obtain a one dimensional integral. In other words:

$\int dy'dz' \frac{e^{\pm ik_{\phi}|\vec{x}-\vec{x}'|}}{|\vec{x}-\vec{x}'|}=\frac{2\pi i}{k_{\phi}}e^{ik_{\phi}(x-x')} ~~~ (I)$

I tried to recalculate equation $(I)$ but got stuck at one point:

I substitute $z-z'=\alpha$, $(x-x')^2+(y-y')^2=\zeta^2$ and finally $\frac{\alpha}{\zeta}=\sinh\beta$. We get then $|\vec{x}-\vec{x}'|=\zeta\cosh\beta$. The double integral in $(I)$ gets:

$\int dy'dz' \frac{e^{\pm ik_{\phi}|\vec{x}-\vec{x}'|}}{|\vec{x}-\vec{x}'|}=\int dy' \zeta\int d\beta e^{\pm ik_{\phi}\zeta\cosh\beta}$

For the last integral I had the idea to shift the integration along the imaginary axis, since there are no poles. If I do that I get

$-i\int dy' \zeta\int_{-\infty}^{\infty} d\kappa e^{\pm ik_{\phi}\zeta\cos\kappa}$

This is almost a Bessel function, but the integration range does not fit. I still have to integrate from $-\infty$ to $\infty$, while I need a $2\pi$ integration range to identify a Bessel function.

I also tried out mathematica, but it did not give me an answer.

Many thanks in advance!