Download four free ebooks about Coahuila that I came across the other day. They contain great historical and great genealogical clues.
My favorite one is the second volume since it contains an article about two of my ancestors, Diego de Montemayor and Alberto del Canto. The article is titled: El Saltillo virreinal en sus orígenes. La pugna entre Montemayor y Del Canto by María Elena Santoscoy.
Yes all these ebooks are in Spanish but if you don't know how to read Spanish you can copy and paste them into google translate.
Let me know in the comments as to which Boletin is your favorite one. Let me know also if you find anything you like.