* {{Cita web| title= The Official Formula 1 website| url= http://www.formula1.com/results/season/1973/496/| accessdate= 2008-01-22| archiveurl= httphttps://web.archive.org/web/20080209143532/http://www.formula1.com/results/season/1973/496/| archivedate= 909 Februaryde 2008febreiro <!--DASHBot-->de 2008| deadurl= no| urlmorta= non}}
* {{Cita web|title=Formula 1 complete - all access F1 - Williamson, Roger|url=http://www.f1complete.com/content/view/432/273/|accessdate=2009-06-19|author=Admin <!-- BOT GENERATED AUTHOR -->|archiveurl=httphttps://www.webcitation.org/5hj1SwNvV?url=http://www.f1complete.com/content/view/432/273/|archivedate=2009-06-22 de xuño de 2009|deadurl=no|urlmorta=si}}
