The hidden message in Tyrann Mathieu's potential number change - Arrowhead Pride
NFL owners pass rule expanding eligible jersey numbers for certain positions
Why some NFL players switched to single-digit jersey numbers - Sports Illustrated
Tulane football players change numbers for various reasons, Tulane
NFL rumors 2021: Proposed rule allowing more players to wear single digits 'likely to pass' (report)
Jersey numbers revealed for Chiefs' new additions
NFL jersey number changes: Why Dalvin Cook, Derwin James and other stars have new numbers for 2022 season
How The Kansas City Chiefs Won The Super Bowl - The New York Times
Single-Digit Jerseys Should Be the NFL's Most Exclusive Club - The Ringer
66 players, including 3 Chiefs, opt out of NFL season due to coronavirus pandemic, FOX 4 Kansas City WDAF-TV
Three Chiefs players have changed their jersey numbers