I appreciate all of the replies. These are providing me a lot of good sources to check, though for the moment I'm trying to avoid foreign sources until I'm sure I've exhausted all domestic ones.

Thanks for the interesting info about the Paris clearinghouse for the captured documents, Artie Bob! I wasn't aware of the logistics of it. I'm starting to think now that perhaps the documents I'm looking for could be England or France (or for that matter Germany) depending on how they could have been divvied up.

On a similar note, I should add that I've seen a lot of references to a large collection of captured documents in the UK. For example, consider this bibliography of the works by Dietrich Küchemann, famous German aerodynamics expert:

https://apps.dtic.mil/docs/citations/ADA044591

Most of the German documents here are listed with GDC numbers. GDC stands for German Document Centre. This appears to be where the UK organized their captured document collection. For all I know a lot of the documents I'm looking for ended up there, but I have no idea how to check that. I haven't found any indices like the US's desk catalog for that collection.