Check out "How to Sing" by Lilli Lehmann and "Raise Your Voice" by Jaime J Vendera. The best guidance with regard to singing would be a voice coach who can guide you in an objective manner, something that would be difficult to glean from the pages of a book. Try combining the info in the books with a good coach.
To be honest, it's very difficult to learn singing techniques from a book. You might prefer to use a dvd or, if you're really serious, to invest in singing lessons.
