History of retired numbers dates back to Lou Gehrig Day
Bill Russell's No. 6 Joins Rare Class of Retired Jersey Numbers - The New York Times
Dodgers celebrate Fernando Valenzuela's number retirement - Los Angeles Times
MLB allows more players to wear No. 21 to honor Roberto Clemente – NBC Sports Chicago
Why don't the Miami Marlins have any retired numbers?
Every MLB team's retired numbers
Mets to retire numbers of Darryl Strawberry, Doc Gooden
Barry Bonds to have No. 25 retired by the Giants
MLB Players Who Defied Father Time into Their 40s, News, Scores, Highlights, Stats, and Rumors
Hank Aaron, Biography, Baseball, & Facts
List of Major League Baseball retired numbers - Wikipedia
Mets to retire numbers of Darryl Strawberry, Doc Gooden
Mets to retire numbers for Doc Gooden and Darryl Strawberry – NBC New York