When I traveled through Mexico and Central America, I carried two guidebooks.
Lonely Planet Mexico
Lonely Planet Central America
You can purchase the Kindle editions of these guidebooks on Amazon and probably other places.
Are you looking for illegal freebies?
I carried a Guia Roji for Mexico, and either just before or just after I crossed into Guatemala, I purchased a fold-out Central American map at a bookstore. I would have preferred a little better map for Central America, but the fold-out was sufficient to get me where I wanted.