It really depends on what details you want to get.
I agree that New Brewing Lager Beer gives a lot of good information on decoction mashing, but that is only a small part of the book.
Kaiser has also made some videos. See
They are not a book, but they give a lot of information, and I found them very useful.
As I said, it depends on what you want to know.
Yes, I have viewed all three sections of his videos and they are really great! But I'm looking for far more information. I have also looked into the late great Greg Noonen's book but once again I'm looking for something more specific to the complete process. It doesn't need to be a "Home"brewing book either, I would be quite happy to read a text book from a brewing university as well. Really, I would like a high level of detail that can not only explain the processes but also it's effects on different types of grain pertaining to recipe creation.