Rick Nash's No. 61 deserves spot in rafters of Nationwide Arena
List of Major League Baseball retired numbers - Wikipedia
Infographic: Packers' retired numbers
Every MLB team's retired numbers
Retired number - Wikipedia
10 Interesting Facts About The NFL - The Fact Site
Kansas City Royals - Wikipedia
Bill Russell's No. 6 Joins Rare Class of Retired Jersey Numbers - The New York Times
Why Kobe Bryant changed jersey numbers and what No. 8 and No. 24 meant to the NBA legend
A number of nuggets about retired numbers around the Major League
Infographic: Packers' retired numbers
History of retired numbers dates back to Lou Gehrig Day
Crunching the Numbers: College Basketball Players Can't Wear 6, 7, 8 or 9 - The New York Times