Eisenstein Series on Siegel Space I am looking for any reference dealing explicitly with Eisenstein series on Siegel space (the simplest case of $\rm{SP}_4$ is fine). Anything would be welcome, but in particular I'm interested in the Fourier-expansions and constant terms. Another preference is that reference be written in the language of the reals instead of the Adeles, though this isn't so important.
Thanks!
UPDATE: Thanks for the references so far! I should have specified, I am interested mostly in the real analytic Eisenstein series, which are induced from the Borel. 
 A: I am going to assume you are asking about the (degenerate) Siegel Eisenstein series on $\mathrm{Sp}(2n)$.  If that is the case, I think you should check out
Piatetski-Shapiro and Rallis, "Rankin triple products", section 4
and
Kudla and Rallis, "Poles of Eisenstein series and $L$-functions".
As far as I am aware, these are the canonical references for the harder analytic properties of the constant term and Fourier expansions of these Eisenstein series.  But they are written in the adelic language, and offer perhaps a more in-depth treatment than you are looking for.  So, you should be able to find an easier treatment just for the case of $\mathrm{Sp}(4)$, but I do not know a reference at the moment.
A: For some reason I did just now remember that an appendix in R. Langlands' SLN 544 does show a classical, non-adelic method to treat (non-cuspidal data) Eisenstein series for $GL_n$ and $Sp_n$. The actual immediate point seemed/seems to be to show how to do this over number fields, paying attention to class numbers greater than $1$, etc., but I recall that when I first saw that years ago there was no easily accessible alternative source that I knew or had heard rumors of.
