NFL execs, coaches tell ESPN - NFL referees need to get better
American football rules - Wikipedia
Replay review in gridiron football - Wikipedia
Don't Blame The Refs For All Of These Replay Reviews
Big Ten officials: Gridiron's not-so secret service
This is the unofficial document that's actually guiding NFL refs
NFL Instant Replay Process
Once upon a further review: Walt Coleman has been doubly
NFL officiating is under fire, putting the Super Bowl crew in the
Highlighting the Responsibility of Each NFL Official
How college football instant replay works: See refs' NCAA rule