Yanks to retire numbers for Williams, Pettitte, Posada

A number of nuggets about retired numbers around the Major League

Which Phillies numbers should be retired? - The Good Phight

Derek Jeter's No. 2, Last of Yankees' Single Digits, to Be Retired - The New York Times

A mathematical examination of when the Yankees will run out of numbers to retire

Core Four - Wikipedia

Yankees to dedicate Mariano Rivera's Monument Park plaque – The Denver Post

Yankees retire Paul O'Neill's No. 21 jersey, Cashman booed

Jorge Posada retires from Yankees at age 40 - The Boston Globe

The Athletic] The Yankees have asked MLB if they can stop issuing uniform numbers to their manager and coaches because they're running out of numbers that aren't retired : r/baseball