Jeter returns as Yankees honor 1998 team at Old-Timers' Day, Boone booed by some
Core Four - Wikipedia
Jeter returns as Yankees honor 1998 team at Old-Timers' Day, Boone booed by some - ABC News
Derek Jeter and the Core Four meet again with Joe Torre, this time as opponents
Core 4 reunited before Yankees' home opener – Daily Freeman
The Core Four – The Talon
Derek Jeter, Mariano Rivera, Andy Pettitte & Jorge Posada Signed Limited Edition Yankees Core Four Authentic Majestic Jersey #27/27 (Steiner COA)
Core 4 saying goodbye to the old Yankee Stadium
Yankees' 'Core Four' is dwindling to one - Los Angeles Times