What is the NFL Guardian Cap? Will it do anything to reduce concussion? — Dr. Mark Heisig
NFL says positions wearing Guardian Caps saw 52% decrease in concussions - NBC Sports
Concussions Dropped More Than 50 Percent for Players Who Wore Guardian Caps, NFL Says, News, Scores, Highlights, Stats, and Rumors
NFL CMO Dr. Sills on Guardian Caps Mandate >> Guardian Sports
Thoughts on Guardian Caps for Concussion Prevention - Smith Physical Therapy & Running Academy
NFL hopes to reduce head injuries with helmet experiment
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
EXPLAINER: NFL using helmet caps for player safety, research - The San Diego Union-Tribune
Coverage of the NFL in Guardian Caps
Players, coaches react to mandatory use of Guardian Caps
EXPLAINER: NFL using helmet caps for player safety, research
Puffy Guardian Caps Could Reduce NFL Player Concussions
Guardian Caps are the latest effort to address CTE, football concussion concerns