Yankees Retired Numbers
How players are using uniform numbers to break MLB's unwritten rules - ESPN
Yankees Retired Numbers
Retired Uniform Numbers in the American League
Eagles Question of the Day: How do you feel about the team's unofficial retired jersey numbers? - Bleeding Green Nation
History of retired numbers dates back to Lou Gehrig Day
NBA players with two different numbers retired
Infographic: Packers' retired numbers
Retired Uniform Numbers in the National League
Twins to retire number for Hall of Fame-elected Kaat - NBC Sports
Fascinating Aspects About the Retired Uniform Numbers of the Detroit Tigers – Society for American Baseball Research
NHL Numbers That Never Should Have Been Retired, News, Scores, Highlights, Stats, and Rumors