Official Boston Bruins Website
Bill Russell's No. 6 Joins Rare Class of Retired Jersey Numbers - The New York Times
Every NBA Team's Retired Numbers - Fadeaway World
List of National Football League retired numbers - Wikipedia
A number of nuggets about retired numbers around the Major League
Southern California teams' retired numbers – Orange County Register
The most random number retirements across all sports
Every MLB team's retired numbers
Most succesful sports teams across global sports leagues