NFL Owners Approve Replay Rule Changes, Among Others for 2021 Season
Baltimore Ravens suggest the NFL add a 'Booth Umpire' in 2021 - Field Gulls
Penalty adjustment to targeting rule could have big effect on games
NFL Replay Officials NFL Football Operations
NFL owners table rule change proposals including onside kick alternative, NFL News
NFL announces major rule changes which will make games last even longer - Mirror Online
NFL teams take care of last-minute business prior to vacation - The Boston Globe
History of Instant Replay
Replay in sports: Ranking the systems from best to worst
A Week With an NFL Officiating Crew, Part III: The Game - Sports Illustrated
History of Instant Replay
Replay review in gridiron football - Wikipedia
More changes may be coming on overtime, replay - NBC Sports