FeldPosts, Documents, and Post Cards
Feldpost and postcards an excellent way of determing locations of the units.
Feldposts
Covers and feldposts with contents.
A 1941 document listing feldpost numbers for the Totenkopf division, numerous polizei battalions and a few other. Source: Prague Military History Records. Reel 2, USHM
Postcards
Usually just a date and a few scribbled words.
Documents
Watch lists, Post war, anything that can fill in details that isn't in an archive.
Miscellaneous Police related
.