The Book of Mules: An Introduction to the Original Hybrid, written and photographed by Donna Campbell Smith, is a celebration of mules, those long-eared hybrids that helped carry pioneers west, tilled the tobacco and cotton fields of the South, and served in the military throughout America history. Today, they are still working hard in fields, working as pack animals, as favorite mounts for trail riders and are still used in the military. The Book...