James Hughes' Mexican Military Arms is a pretty good book on a subject not often written about. It covers all the rifles used by the Mexican Army (both locally designed and purchased elsewhere) from the Spencer repeater up to the adoption of the M1 Garand. It is a bit limited in coverage, though, with a single page for most of the guns it includes. The photos also range from good to almost unusable. Overall, it's definitely worth having as long as you have an interest in this particular topic. You can find it for sale in the link below, though the prices being asked on eBay and Amazon are pretty outrageous.