"Variation in Top Level Soccer Match Performance"
Authors E. Rampinini, A. J. Coutts, C. Castagna, R. Sassi, F. M. Impellizzeri


https://docs.google.com/open?id=0B79pwHjrNL1eZmEyY2Y4Y2EtMTk3NS00OTk0LTg3NjAtOGNkOWNmODlkMDE3