The Packer's Bible.  We consider this pre-eminent and required reading for any backcountry packer.  At times funny, always helpful, it's one of the best compilations of the knowledge needed when packing mules and horses in the wilderness.  Illustrated by the author himself, we highly recommend this for all readers.
NOTE:This is a "used" book and has an inscription on the inside cover.  However, it is in "Like New" condition otherwise.