History of retired numbers dates back to Lou Gehrig Day
Lou Gehrig at age 29, of The New York Yankees in spring training
Lou Gehrig - New World Encyclopedia
Lou Gehrig retires, gives 'Luckiest man on the face of the earth
Every MLB team's retired numbers
Yankees retired numbers
Derek Jeter's No. 2, Last of Yankees' Single Digits, to Be Retired
Yankees to retire Paul O'Neill's No. 21: See the complete list of
MLB celebrates second annual Lou Gehrig Day
Yankees retired numbers
Pack has retired just six uniform numbers - Hub City Times
Lou Gehrig is the most Ruthian Yankee of all time - Pinstripe Alley
History of retired numbers dates back to Lou Gehrig Day
Every MLB team's retired numbers – NBC Sports Chicago
Yankees retired numbers and the baseball legends who wore them