Hi,
Some (or perhaps all) pages of the files in Findbuch 12452 can be downloaded (page by page).
As example here the link to the first page of file 623 :
http://wwii.germandocsinrussia.org/pages/285061/zooms/8
The next page be downloaded by changing the nr 285061 to 285062
http://wwii.germandocsinrussia.org/pages/285062/zooms/8
This procedure can be applied to download all the pages, but it is very time consuming.
Best regards
Luc