On Beginning to Read Foucault

I'm starting to read Foucault, and am particularly interested in his more
theoretical formulations of his views.  I have read "Nietzsche, Genealogy
and History", and was interested in further writing F did on both his
relation to Nietzsche's work, and how he understood the status of a
historicist critique of philosophy, truth and rationality such as his own.
Any help would be appreciated,

                Gabriel Benaim