Peterson Field Guide to Mammals of North AmericaRoger Tory Peterson's unique system shows exactly what features to look for to tell one species from another. Peterson Field Guides are designed to work in the field, and every illustration, every word, is directed to that end. For each Field Guide, an author with expertise in the subject and an experienced artist work closely with the editors to ensure that both text and illustrations are accurate. As the most comprehensive and in depth guide to