Yugoslavian inland tow barge Sv. Prokop seen April 1941

An item referred to a letter of the Aussenstelle Bukarest der Etra Sudöst dated 30 April 1941 to the Etra Sudöst at Wien, Austria reporting the presence of Yugoslavian ships seen on the route Bazias, Romania-Belgrad, Yugoslavia nowadays Serbia during the survey voyage of the steamship Isper of the Räumkommando Bukarest, Romania. On the position Ramaer Arm 1077-1101 1 kilometre above Kostolac, Serbia empty undamaged  

Source

High Command of the Kriegsmarine (OKM). Case 86