College football's less draconian pass interference penalty is better than NFL's - Land-Grant Holy Land
NFL referee Tony Corrente explains controversial calls against Bears, Cassius Marsh in loss to Steelers
Common NCAA football penalties and referee hand signals - CougCenter
18 Football Referee Signals (Ultimate Guide With Images)
NFL Referees Are Breaking Records With The Amount Of Penalties Being Called Through Week 2 - Daily Snark
Referee Ron Torbert officiated Cincinnati's Super Bowl 56 loss
Great Call Athletics, Professional Football Penalty Flag, All Pink Breast Cancer Awareness Referee Lacrosse Official
VIDEO: Ever Wonder What Referees Are Really Signalling?
Patriots expected Jerome Boger to call more penalties on them than on the Panthers - Pats Pulpit
NFL's Week 6 officiating was embarrassing
NFL referees calling one particular penalty more often
Analyzing Defensive Pass Interference Fouls in the NFL and NCAA
What Are The Most Common Penalties In NFL Football?
Seeing yellow: The data behind penalties in the NFL