Given a global field $F$ and a reductive group $G$, where can I find the spectral decomposition of $ L^2( Z(\mathbb{A}) G(F) \backslash G( \mathbb{A})).$
I will need the result in this generality, means for a general reductive group and for function and number fields.
I have just seen some instances of such theorems yet and would be happy about a reference. Of course, I expect that the function field and number field case have been treated, but probably in different places.