NFL uniform rules and regulations are strict, in a good way - Sports Illustrated
The NFL has officially passed the expanded jersey number rule : r/Tennesseetitans
NFL rule proposal would allow more players to wear single-digit numbers like in college football
NFL jersey number restrictions could change for running backs, receivers, tight ends, linebackers, defensive backs
Tom Brady slams NFL's jersey number rule: 'Dumb'
NFL jersey number restrictions could change for running backs, receivers, tight ends, linebackers, defensive backs
Uniform number (American football) - Wikipedia
NFL Relaxes Restrictions on Jersey Numbers - The New York Times
Eagles unveil jersey numbers; D'Andre Swift to wear No. 0
Why some NFL players switched to single-digit jersey numbers - Sports Illustrated
Evolution of the NFL Player
NFL jersey number rule change could bring back some classic college football looks for Derrick Henry, Jalen Ramsey and others - ESPN
Single-Digit Jerseys Should Be the NFL's Most Exclusive Club - The Ringer
NFL jersey number rule change could bring back some classic college football looks for Derrick Henry, Jalen Ramsey and others - ESPN
NFL reportedly passes new jersey number rules: Who can wear what under revised guidelines