Andy Pettitte once revealed that Roger Clemens had introduced him

Roger Clemens - Wikipedia

World Series: Yankee Doodle Andy does it in style

Witness says he saw Clemens at Canseco pool party

Pettitte thriving in new set of pinstripes

Yankees' Andy Pettitte announces he will retire

Andy Pettitte, Roger Clemens still pitching, but from different angles - The Boston Globe

Roger Clemens, Baseball Wiki

Mussina says Pettitte will face challenges

Mel Antonen: Voters say Andy Pettitte comes up short by Hall of Fame standards - Sports Illustrated

Andy Pettitte Timeline: Yankees pitcher forever linked to Roger Clemens and baseball's PED era – New York Daily News

Andy Pettitte on first Hall of Fame ballot

Yankees sign Andy Pettitte out of retirement