Invariance under diffeomorphisms of the Sobolev $H^s$ spaces

Question

Let $\Omega, \Omega' \subset \mathbb{R}^n$ be two open subsets and let $\psi : \Omega \rightarrow \Omega'$ be a $C^k$ diffeomorphism. Then, $\psi$ induces by pullback a linear isomorphism $$u \mapsto u \circ \psi$$ between the Sobolev spaces $W^{k,p}_{\text{loc}}(\Omega')$ and $W^{k,p}_{\text{loc}}(\Omega)$. I assume that there is an analogous result for the Hilbert-Sobolev spaces $H^s_{\text{loc}}(\Omega)$ with real exponent $s$. Can someone please provide me a reference where this is discussed?