Official (gridiron football) - Wikipedia
NFHS announces seven new rules for the 2022 high school football season - High School Football America
NFL passes rule allowing single-digit jerseys for skill players
NFL jersey number rule change could bring back some classic college football looks for Derrick Henry, Jalen Ramsey and others - ESPN
NFL jersey numbers: Odell Beckham Jr., Stefon Diggs among 20 big names who could make switch under new rule
NFL Could Be Easing Up On Jersey Number Restrictions, Would Be A Fine Move - Sports Illustrated Cleveland Browns News, Analysis and More
NFL Approves Proposal That Loosens Restrictions on Jersey Numbers - Sports Illustrated Cincinnati Bengals News, Analysis and More
NFL rumors 2021: Proposed rule allowing more players to wear single digits 'likely to pass' (report)
Worst Rule Changes in NFL History
NFL100: Before they were zebras, they were … candy canes? – Football Zebras
Why some NFL players switched to single-digit jersey numbers - Sports Illustrated