File:Mariano Rivera's cutter grip traced onto ball for Roy Halladay at Baseball Hall of Fame.jpg - Wikipedia

Championship Year in Review: From April to October, in their own words - Giants Extra

One baseball connects two 2019 Hall of Fame inductees

Mariano Rivera looks back on teaching Roy Halladay his legendary cutter

Yankees 'Overnight Babe Ruth' Shocks New York With Favorite Meal

At the 2008 All-Star Game, Mariano Rivera taught Roy Halladay his famous cutter. Halladay traced the outline of the grip onto the ball, and kept it in his locker for the rest

What Mariano Rivera Shared With Roy Halladay, Besides Hall of Fame Credentials - The New York Times

The Baseball Analysts: Baseball Beat Archives

One baseball connects two 2019 Hall of Fame inductees

Yankees legend Mariano Rivera inducted into Baseball Hall of Fame: 'I tried to carry the pinstripes the best that I could'

Yankees weren't happy when Mariano Rivera showed Roy Halladay his cutter