Let $K$ be a real quadratic number field and $\mathcal O_K$ its ring of integers. Then $$q:K\to \mathbb Q,\quad q(x):=\operatorname{tr}(x^2)/2$$ turns $\mathcal O_K$ into a positive definite lattice ($q$ is the quadratic form associated to the trace form $(x,y)\mapsto \operatorname{tr}(xy)$). So we can talk about the Epstein zeta function $$\zeta({q,s}) := \sum_{0 \ne x \in \mathcal O_K} q(x)^{-s} = 2^s\sum_{0 \ne x \in \mathcal O_K} \operatorname{tr}(x^2)^{-s}.$$
I want to learn more about this zeta function. Is there a connetion to the Dedekind zeta function? Where can I read more about it?