A book I found gave a bit of insight into this sort of behaviour and was easy to read was - Jim Heath "Your Dog is Watching You" . Gives a background on dog behaviour without bogging you down. It opened my eyes about the tricks our pawed friends get up to to wrap us round their dew claws.
But I too would also get a good behaviuorist to help you out if you feel you don't understand enough to read the sutble signs (or not so sutble in this case) of canine body language.
Matt