David V. Herlihy: Bicycle: History. Yale University Press, 2004, ISBN 0-300-10418-9, S.246 (google.com): „The popular Whippet incorporated a series of external springs suspending the entire frame.“
Wiebe E. Bijker: Of Bicycles, Bakelites, and Bulbs: Toward a Theory of Sociotechnical Change. The MIT Press, 1997, S.73 (google.com): „Even the successful „Whippet“ with its many movable parts needed more attention than an ordinary bicycle.“
espacenet.com
worldwide.espacenet.com
Patent US5509679A: Rear suspension for bicycles. Angemeldet am 9. September 1994, veröffentlicht am 23. April 1996, Anmelder: 89908 Inc, Erfinder: Horst Leitner.
Patent US5678837A: Rear suspension for bicycles. Angemeldet am 16. April 1996, veröffentlicht am 21. Oktober 1997, Erfinder: Horst Leitner.
Patent USRE39159E: Bicycle wheel travel path for selectively applying chainstay lengthening effect and apparatus for providing same. Angemeldet am 27. März 2003, veröffentlicht am 11. Juli 2006, Anmelder: Santa Cruz Bicycles Inc, Erfinder: James B. Klassen, Jamie W. Calon.