Of course, there is "Facundo: Civilization and Barbarism" written by one of Rosas's successors (and one of the founders of public schooling in the western hemisphere) Fausto Sarmiento.
Thank you! I could probably get through a history in Spanish, with a little help from the on-line dictionary, but I’m on a Henry James binge in every spare minute right now :-).
I’ll look for the English books you mention in the library this week. All the years of Spanish language and culture courses, and I have to admit I know almost nothing about Argentina. Gauchos.