Hi
As far I am aware of, it still today exist a huge amount of historical aviation material in Breslau in Silesia.
The Polish have refused to give the material "back to" Germans institutions despite several proposals. The material have also been secret until today (at least for German researchers)...
I dont like this behavior...

, but I shall admit that a few German institutions/archives behave similar or make its very difficult to get access to important historic information..
The only good thing is that the material is "still there" and that the Polish perhaps in the future will change their attitude..
Gunnar