Giants' Coughlin Masters the Art of Throwing a Red Flag - WSJ
Inside the often-chaotic NFL challenge process - ESPN
Giants' Coughlin Masters the Art of Throwing a Red Flag - WSJ
Why throwing challenge flag is different in Super Bowl - Sports Illustrated
NFL fans amused by Bill Belichick's sassy challenge flag throw – NBC Boston
Watch: Patriots HC Bill Belichick shows disdain for officials
Which NFL head coaches are the best/worst challengers?
How Do NFL Coaches Use Their Challenges?
Brock Purdy throws 4 TD passes to lead the 49ers past the Cowboys 42-10
383 Nfl Coach Challenge Flag Stock Photos, High-Res Pictures, and Images - Getty Images
383 Nfl Coach Challenge Flag Stock Photos, High-Res Pictures, and Images - Getty Images
Part 2: How good (or bad) is Seahawks coach Pete Carroll on challenges? - Field Gulls
Bill Belichick Throws Challenge Flag Like A Petulant Child Toward Ref's Face