There are many good resources available today that explain the connection between animals and humans. Most of the books listed below are probably available on Amazon. I have listed some of my favorites.
Animal Assisted Activities & Therapy:
Animal Assisted Therapy in Counseling by Cynthia K. Chandler
Blue Dog Book(s) by Melissa Y. Winkle - there are several books in this series- available through Dogwood Therapy Services, - www.dogwoodtherapy.com
101 Creative Ideas for Animal Assisted Therapy: Interventions for AAT Teams and Working Professionals by Stacy Grover
Animal-Assisted Interventions for individuals with Autism by Merope Pavlides
Animal Assisted Therapy Activities to Motivate and Inspire by Nancy Lind
Delta Society - Pet Partners - is also a rich resource for information on animal assisted activities, therapy, and animal training programs.