Looking for bills of lading of 7 barges with "special" cargo

Hello everybody! A friend of mine is currently working on a book on the end of World War II in the German town of Straubing. I am helping him out with translating his research requests into English.

Straubing (coordinates UQ 22/17) is situated by the river DANUBE between the cities of REGENSBURG and DEGGENDORF in the state of Bavaria. The studies of the U.S. Historical Division state that – during the takeover of defense sector Deggendorf-Straubing-Giesling on the 26th of April 1945 – the 36th V. G. D. of the German Wehrmacht found seven barges by Straubing on the Danube, loaded with approximately 5,000 tons of poison gas bombs (Tabun/Sarin) belonging to the German Luftwaffe.

Thus, the 36th V. G. D. made an agreement with US troops to install a neutral zone around Straubing. Subsequently, the seven barges, their cargo, their personnel and the bills of lading were handed over to US troops on 26 April 1945. After that, the front of the 36th V. G. D. was not attacked by US troops.

Where, do you think, can he find the bills of lading of these seven barges? I am aware that this is a somewhat special request but I am hoping, that, if anywhere, the users at History Hub might be able to help us with our research.