Yankees retire Paul O'Neill's No. 21 jersey, Cashman booed
History of the New York Yankees - Wikipedia
Yankees retired numbers and the baseball legends who wore them
Elston Howard - Wikipedia
Yankees retired numbers
The Greatest Living Yankees from the past half-century - Pinstripe Alley
Jasson Domínguez's first homer in New York helps Yankees get back over .500 with win over Tigers - The Boston Globe
Judge hits 3 home runs, becomes first Yankees player to do it twice in one season
New York Yankees retire Paul O'Neill's No. 21; GM Brian Cashman, owner Hal Steinbrenner booed by fans - ESPN