Bill Russell's No. 6 Joins Rare Class of Retired Jersey Numbers - The New York Times
The only day MLB players can wear No. 42? Jackie Robinson Day
History of retired numbers dates back to Lou Gehrig Day
Petition Roberto Clemente number 21 have to be retired from all MLB teams
Manager Numbers. Had a little fun over at MLB — I picked…, by Joe Posnanski, Joe Blogs
List of Major League Baseball retired numbers - Wikipedia
Retired numbers in Phillies team history Phillies Nation - Your source for Philadelphia Phillies news, opinion, history, rumors, events, and other fun stuff.
Every MLB team's retired numbers
Ranking MLB Teams With the Most Retired Numbers of All-Time