The Jensen's formula says the following: Let $f$ be analytic on the disc $D$ of radius $R$ centered at the origin such that $f(0)\neq 0$, then \begin{align} \log(|f(0)|)+ \sum_{i=1}^n \log \left(\frac{R}{a_i} \right ) = \frac{1}{2\pi}\int_0^{2\pi}\log(|f(Re^{i\theta})|)d\theta, \end{align} where $a_i$'s are zerof of $f$ in $D$.

Are there extensions of this theorem to regions other than discs. For example, does it hold of rectangular regions?