In the past, the IAQG had "discouraged" unofficial interpretation material. As Howste mentioned, the standard has not been released yet. So, if there was a book available already would have to have come from someone with access to the draft of the standard and that could be considered by some as "unethical" as inside trading like practices....
I agree that the
best source for interpretational issues on the standard is the material coming from the IAQG themselves. For example, for the Rev. C of the AS9100 standard we have
It is likely we will see similar documents for the AS9100 Rev. D document.