"NULLØSNING PÅ FRIENDS ARENA" (in Danish). Denmark Football Association. 2 June 2018. Archived from the original on 12 September 2020. Retrieved 12 September 2020.
"HER ER DANMARKS VM-TRUP" (in Danish). Denmark Football Association. 4 June 2018. Archived from the original on 16 November 2019. Retrieved 12 September 2020.
"Friedrich redet Klartext" (in German). Wolfsburger Allgemeine. 15 December 2010. Archived from the original on 9 September 2020. Retrieved 12 September 2020.
"Der VfL mit Zauberfußball!" (in German). Wolfsburger Allgemeine. 25 November 2010. Archived from the original on 9 September 2020. Retrieved 12 September 2020.
"Wer rettet den VfL heute?" (in German). Wolfsburger Allgemeine. 19 October 2012. Archived from the original on 10 September 2020. Retrieved 12 September 2020.
"Friedrich redet Klartext" (in German). Wolfsburger Allgemeine. 15 December 2010. Archived from the original on 9 September 2020. Retrieved 12 September 2020.
"Der VfL mit Zauberfußball!" (in German). Wolfsburger Allgemeine. 25 November 2010. Archived from the original on 9 September 2020. Retrieved 12 September 2020.
"Wer rettet den VfL heute?" (in German). Wolfsburger Allgemeine. 19 October 2012. Archived from the original on 10 September 2020. Retrieved 12 September 2020.
"NULLØSNING PÅ FRIENDS ARENA" (in Danish). Denmark Football Association. 2 June 2018. Archived from the original on 12 September 2020. Retrieved 12 September 2020.
"HER ER DANMARKS VM-TRUP" (in Danish). Denmark Football Association. 4 June 2018. Archived from the original on 16 November 2019. Retrieved 12 September 2020.