The Philidor files by Christian Bauer, Everyman Chess 2006
BTW there is a strong case for entering Philidor via 1.e4 d6 2. d4 Nf6 3.Nc3 and now either 3...e5 or 3...Nd7, and the book covers these lines as well. But, having said that, I'd stick with 3...g6
