Appreciating the retired single-digit numbers of the New York Yankees
As Paul O'Neill's No. 21 Is Retired, One Last Kick of a Water Cooler - The New York Times
Yankees retire Mariano Rivera's number
Yankees retired numbers: A look at all of the jersey numbers players cannot wear in the Bronx
Yankees retire Paul O'Neill's No. 21 jersey - NBC Sports
New York Yankees Retired Numbers - - Database of Yankee Uniform Numbers Through the Years
Should the New York Yankees retire Alex Rodriguez's number?
New York Yankees: 5 numbers that need to be un-retired
New York Yankees retired Paul O'Neill's No. 21 jersey
New York Yankees Retired Numbers - Sports Illustrated
Yankees Retired Numbers - Who Are The 22 Yankees Who Wore Them