Best book on dog language, ever.
http://www.amazon.com/Talking-Terms-Dogs-Calming-Signals-ebook/dp/B003URRK44/ref=sr_1_1?s=books&ie=UTF8&qid=1398567951&sr=1-1&keywords=on+talking+terms+with+dogs+calming+signals
I like Turid. She has been criticized for going too far with her signals but I love her videos.