Well, now you guys had me curious about the two different books by Griehl so I had a look.
The older one, published in 2006, shows that it has only 80 pages. This new one published last year has, like I mentioned earlier, 280 pages and is by a different publisher entirely.
Not sure why the big difference between the two. Perhaps the older publication was more of a preliminary work and the latest is the result of deeper research.
I did see in the credits of my book, that Griehl sourced some pretty impressive origins, including former manufacturers and families of the people responsable for the design and construction of the aircraft.