1. Επίσημη ιστοσελίδα Mayo Clinic, www.mayoclinic.org/diseases-conditions/spinal-cord-injury/symptoms-causes/syc-20377890
2. Erik Witvrouw, PT, PhD, Roeland Lysens, MD, PhD, Johan Bellemans, MD, PhD, Dirk Cambier, PT, PhD, Guy Vanderstraeten, MD, PhD Intrinsic Risk Factors for the Development of Anterior Knee Pain in an Athletic Population: A Two-Year Prospective Study, Vol: 28 iss: 4, p: 480-489. Published: July 1, 2000 "