Another book worth a look is Ken Mondsheins new "The Art of the two handed sword".
It has a few translations of some Spadone sources in the first part, the best of which is the two handed stuff from the Riccardiano.
The best bit of the book though is the second part where he applies fencing theory to a two-handed sword (nominally Spadone but he has been very open that he is really pitching it at any part of HEMA), he references all the books (and more) that Phil mentioned but also shows how it can be used. It has definitely given me a lot to think about. I believe that there is some merit in taking a modified version of this approach (respecting your sources) and then applying the source you study over the top.
So I think that it is a very good intro to showing how the classical fencing sources can be adapted to our context. Even if you don't agree with his approach there is a lot to learn I think, to me it seems to fit in with the general theme I have wanted to explore and what a few others have been finding - that general fencing concepts are still very important to us in HEMA.
Context is everything