@misc{SponagelGrafGross2007,
  author    = {Stefan Sponagel and G{\"u}nter Graf and Heinz Groß},
  title     = {Method for manufacturing a sealing ring : United States Patent 4,861,536 ; date of patent: Aug. 12, 1989 / assignee: Firma Carl Freudenberg. Inventors: Gunter Graf ; Heinz Gross ; Stefan Sponagel},
  institution = {Fachbereich Medizintechnik und Technomathematik},
  type      = {patent},
  pages     = {5 S. : Ill.},
  year        = {2007},
}