I am looking for references on unitary groups in the algebraic setting: that is, given a quadratic extension $E/F$, the unitary groups (if I understand correctly) are subgroups of the Weil restriction of scalars of $GL(n)$ from $E$ down to $F$, which are fixed by some involution. More specifically, I am looking for some sort of classification, which ones are quasi-split, if they are simply-connected (or with simply-connected derived subgroup), etc. Does anyone know where to look?
I give an answer to my question so that it does not go unanswered.
A good reference on unitary groups in general is (as B R suggested) the book Algebraic Groups and Number theory by Platonov and Rapinchuk, especially Chapter 2 and 6. Another good reference is The Book of Involutions by Knus et al.
Also, I found great lecture notes by Bellaiche, Automorphic forms for Unitary groups and Galois representations.
Finally, the book Automorphic representations of unitary groups in three variables by Rogawski has a nice discussion on many things, in particular Cartan subgroups of unitary groups.