UCLA study shows NFL jersey numbers impact performance - Los Angeles Times
Tom Brady slams NFL's jersey number rule: 'Dumb'
The NFL's new single-digit jerseys are inspiring excitement and a little grumbling - The Washington Post
The NFL Jersey Number Rule Explained - HowTheyPlay
New NFL jersey numbers, explained: What to know about league's rule change for 2021
2021 N.F.L. Rule Changes: A Viewer's Guide - The New York Times
NFL jersey number restrictions could change for running backs, receivers, tight ends, linebackers, defensive backs
NFL jersey number restrictions could change for running backs, receivers, tight ends, linebackers, defensive backs
The NFL's 6 new rules for the 2021 season, explained