False claims of NFL referee investigation started as satire
Officials' Responsibilities & Positions
The First All-Black NFL Officiating Crew Made History
NFL to Make History With All-Black Officiating Crew for Monday's Rams-Bucs Game – NBC 7 San Diego
NFL fires ref who missed easy call in Browns game. That's unprecedented
NFL Officials: Preparing for Success
How much do NFL referees make? - Zippia
NFL Referee gets crowd's attention before making a call
How much money do referees make during NFL playoffs? – NBC Sports Bay Area & California