* [http://www.ncaapublications.com/Uploads/PDF/Football_Rules_5_2204c0005d-845f-4813-8391-54f15136079d.pdf NCAA's complete college football rules; available as a PDF file]{{Liên kết hỏng|date=2021-01-26 |bot=InternetArchiveBot }}
* [http://memory.loc.gov/cgi-bin/query/S?ammem/papr:@FILREQ(@field(TITLE+@od1(Chicago-Michigan+football+game++))+@FIELD(COLLID+workleis)) Movie of 1903 football game between the University of Chicago and the University of Michigan]
* National Football League [http://www.nfl.com/rulebook/signals Official Signals].
* [http://www.unc.edu/depts/nccsi/SurveyofFootballInjuries.htm Annual Survey of Football Injury Research]
* [http://news.bbc.co.uk/sport1/hi/other_sports/american_football/3192002.stm Brief explanation of the sport by the BBC aimed at a non-american audience]
