This is a common issue -- and this is a well-reviewed book from a great trainer that should be of help:
http://www.phantompub.com/HelpForYourFearfulDogBook.htm
I imagine you could order it through Amazon or your local bookshop too.
http://www.phantompub.com/HelpForYourFearfulDogBook.htm
I imagine you could order it through Amazon or your local bookshop too.