GPZ06 was what became known as the "semi-official" Strike Witches doujin peddled off at 2008's Winter Comiket by the series director Kazuhiro Takamura. This particular work has no erotic content, stories, or even 4-koma; No, this book is merely 35 pages or so of production materials for the anime.
There are a couple original images of Lynette (in B&W) and then a clean B&W version of the cover image. There is also a single page containing a wall of text, and a picture of a can of SPEM with Shirley on it. However, everything is clean lineart for the DVD covers, and a bunch of pencil work for scenes in the series.
It is worth noting that much of the scenes focused on in this book are the bathing and swimming bits. I assume this is because Takamura felt that they had extreme artistic value, and were a high point in his career. I can figure no other possible explanation.
There's also a page that is full of nothing but the girls' derrieres, and the caption "Whose is it hip?" challenging you to identify the girls using nothing but their badonkadonk. Can you do it?
It is also worth noting that while the scans start at page 03, there isn't actually any page 01 or page 02 in the book. There was a piece of blank orange paper inserted before it, so maybe that was considered to be the first two? Who knows. In any case, nothing is missing.
Go ahead and get it down here:
Strike Witches - GPZ06
Coming soon, the Shadow of The Colossus doujin "Kyozou Musume"(as soon as it arrives in the mail ((any day now)) and I make some decent scans):