American football rules - Wikipedia
Instant replay hi-res stock photography and images - Alamy
Instant Replay Game: 25 years later
Upon Further Review: A Brief History of Instant Replay
NFL replay reviews, challenges drop with new rules and tech - ESPN
Instant Replay: What stood out in Falcons game vs. Pittsburgh Steelers
He Invented Instant Replay, The TV Trick We Now Take For Granted : The Two-Way : NPR
The Invention of Instant Replay Lemelson Center for the Study of Invention and Innovation
Another Pro Football League Is Born. Will It Outdo the (Short-Lived) Others? - The New York Times
NFL Annual League Meeting 2018: Grades on new rules, news, and notes
Football Games Have 11 Minutes of Action - WSJ
The CFL has figured instant replay out. How long until the NFL and CFB follow suit? - Footballscoop
NFL's instant replay officials have new powers, but owners weren't interested in other major rules changes - The Boston Globe