With 1128 pages, it should really be the reference book about this town in WWII...
You can buy it online at
http://www.thiel.at/main.htm (second of the list on my screen) for 60 euros... or at least that is how I understand it after a quick scan of the site (German is not my best language).
If you buy it, I will be interested in a short review of what is inside this large book.