List of Major League Baseball retired numbers - Wikipedia
The Players Who Wore Retired Numbers Before They Were Retired
How many uniform numbers are retired by the New England Patriots?
Every MLB team's retired numbers
Which NBA players have had their jersey retired by multiple franchises?
Infographic: Packers' retired numbers
Why is BYU basketball freshman Steven Beo wearing a retired jersey number? - Vanquish The Foe
Canadiens' Retired Jerseys - the Story of a Famed Franchise
Why the Miami Heat retired Michael Jordan's jersey - Sports Illustrated Chicago Bulls News, Analysis and More
Dan Marino should let Tua Tagovailo wear No. 13
Complete list of retired numbers in the NBA - AS USA
Colorado allows football players to wear 3 retired numbers
Crunching the Numbers: College Basketball Players Can't Wear 6, 7, 8 or 9 - The New York Times
Da Greats: Retired Chicago Bears Jersey Numbers - The Chicago Audible