List of National Football League retired numbers - Wikipedia
Retired number - Wikipedia
A number of nuggets about retired numbers around the Major League
Bill Russell's No. 6 Joins Rare Class of Retired Jersey Numbers - The New York Times
Every MLB team's retired numbers
Are there any jersey numbers that are retired across all teams? - Quora
Oldest Sports Teams in the US - State by State [MAP] : r/sports
The most random number retirements across all sports
Only 3 Legendary Athletes Have Their Numbers Retired League Wide - The Spun: What's Trending In The Sports World Today
App State to Retire Armanti Edwards' Number 14 - App State Athletics
Da Greats: Retired Chicago Bears Jersey Numbers - The Chicago Audible