Pinstripe Prestige: Yankee Numbers Most Likely Headed For Monument Park, News, Scores, Highlights, Stats, and Rumors
Yankees want to stop issuing uniform numbers to managers, coaches because they're running out
Yankees to retire Paul O'Neill's No. 21 on Aug. 21
Numbers up: Aaron Judge not the only Yankee in the 90s on his jersey - Newsday
The Yankees Retire Paul O'Neill's Number 21 - The New York Times
Appreciating the retired single-digit numbers of the New York Yankees
Yankees Retired Numbers - Who Are The 22 Yankees Who Wore Them
New York Yankees Retired Numbers - Sports Illustrated
Number 21 Continues to Remain Sacred to the New York Yankees, News, Scores, Highlights, Stats, and Rumors
As cases for Roy Halladay and Dick Allen point out, baseball's retired numbers are multiplying
New York Yankees - Wikipedia