Here are some books on animal communication, inspirational success stories and guidance and methods for learning this communication skill.

Penelope Smith - "Animal Talk", "When Animals Speak", "Animals in Spirit"

Carol Gurney - "The Language of Animals: 7 Steps to Communicating with Animals"

Pea Horsley - "Heart to Heart", "Life Loss Love", "Animal Communication Made Easy" 

Marta Williams - "My Animal My Self", "Learning Their Language", "Beyond Words", "Ask Your Animal"