Following on from Chris's comment, Nigel Parker's excellent L
uftwaffe Crash Archive Volume p.61-63 (Red Kite/Wingleader 2013) has a series of photos of D-ASUO and a short Intelligence Report. If you can't get hold of a copy pm me with your email address and I will scan the pages for you.
I can't find any other instance of 'captured' He 59s, a number were lost at sea and some were sunk at their moorings in storms. There is a pretty complete list of He 59 and other Luftwaffe maritime losses at:
http://www.luftwaffe-zur-see.de/Seel...n/Jahr1940.htm
For additional information Chris's
Sea Eagles Volume 1 (Classic Publications, 2005) is a very good overview of Luftwaffe anti-shipping units 1939-41, and includes photos and some excellent colour profiles of He 59s.
Samaritans or Spies, is a good article by Andrew Thomas in
Luftwaffe Eagles, Battle of Britain Special, ed. Ken Ellis (Key Publishing, 2015) which includes colour profiles of D-ASUO and many photographs.
More general works that include coverage of the He 59 are:
Aufklärer, Bomber, Seenotretter. See-Mehrzweckflugzeuge Heinkel He 59 und He 115, by Christian König (Helios Verlag, 2020).
Rettung zwischen den Fronten: Seenotdienst der deutschen Luftwaffe 1939-1945, by Karl Born (Taschenbuch, 2001).
Eagles over the Sea: a History of Luftwaffe Maritime Operations 1939-42, by Lawrence Paterson (Seaforth Publishing, 2019).
I hope that this helps.
Peter