Universitäts-und Landesbibliothek Bonn (October 2003). "Geschichte der ULB Bonn". Archived from the original on 27 November 2007. Retrieved 8 February 2008.
Universitäts-und Landesbibliothek Bonn (October 2003). "Geschichte der ULB Bonn". Archived from the original on 27 November 2007. Retrieved 8 February 2008.