Dearings book is the best dragon book.
However, there has been several developments in most lines. For exampel in critical 9 0-0-0 line with 12 Bd4, Dearings main recommendation e5 is not in good shape anymore. Fortuannly both Bxd4 and Nxc3 are playable. There has also been developments for both sides in 9 0-0-0 d5 10 Kb1 line.
You also have to decide is you want to allow 9 Bc4 yugoslav with 12 Kb1 or not. There has been several development in Topalovs Rc8 Nxd4 b5. Also, there has been several devlopments in 12 Kb1 Nc4 for black in Burnett variation and several for white in Re8 h4 h5 g4 lines. It can recommend the link bellow to get you started.

http://openingtheory.wordpress.com/

I've been a Najdorf player for a few years and I've decided I want to learn the Dragon in order to have another option whilst still in the Sicilian family. 

If anyone could recommend the "must have" dragon books I would greatly appreciate it, after which I can just update the lines from the book using chess pub I hope.