Does anyone know of a book/website where I can find a proof of the Von-Mangoldt Explicit Formula? Namely;

$\displaystyle \psi (x) = x - \displaystyle\sum_{\rho}\frac{x^\rho}{\rho}\ - \frac{1}{2}\ ln(1 - \frac{1}{x^{2}}) - ln(2\pi)\$

where the rhos are the zeta zeros whose real parts are less than 1.

Thanks in advance!