"Memorandum of Understanding"(PDF) (in German). Federal Ministry of Transport, Building and Urban Affairs. 19 July 2007. Archived from the original(PDF) on 2020-04-14. Retrieved 2007-07-20.
"Memorandum of Understanding"(PDF) (in German). Federal Ministry of Transport, Building and Urban Affairs. 19 July 2007. Archived from the original(PDF) on 2020-04-14. Retrieved 2007-07-20.