List of National Football League retired numbers - Wikipedia
Southern California teams' retired numbers – Orange County Register
Bill Russell's No. 6 Joins Rare Class of Retired Jersey Numbers - The New York Times
How many sports teams can you name that don't end in S? - Quora
Giants Team New York Giants –
List of National Football League retired numbers - Wikipedia
Bill Russell's No. 6 Joins Rare Class of Retired Jersey Numbers - The New York Times
Every MLB team's retired numbers – NBC Sports Chicago
Kansas City Royals - Wikipedia
Which NBA team has the most jersey numbers retired? - AS USA