7 totally unique ways NFL officials have robbed Detroit Lions this decade
The Real Reason Why Football Referees Throw Yellow Penalty Flags
How the NFL is manipulating games in 2020 - Fewer holding calls, faster games and way more offense - ESPN
NFL referees throw record-breaking amount of flags - The Aggie
Marcus Peters throws refereee flag into stands, fed up vs. Jets - Sports Illustrated
Head of NFL Referees Association throws flag on fans who think refs are biased against their team
Chiefs vs Raiders: Referee defends roughing the passer call
Column: Throw a flag on these NFL refs - WTOP News
NFL Rulebook NFL Football Operations
Where have all of the NFL points gone?
NFL Football Penalties Explained - HowTheyPlay