Kracht, Claudia (15 January 2008). "Der Bundesliga-Skandal 1971" (in German). Planet Wissen. Archived from the original on 8 February 2009. Retrieved 10 December 2008.
Kracht, Claudia (15 January 2008). "Der Bundesliga-Skandal 1971" (in German). Planet Wissen. Archived from the original on 8 February 2009. Retrieved 10 December 2008.