The N.F.L. Struggles to Tackle Its Latest Problem: Tackling - The New York Times
How football helmets fail to protect against some of the most dangerous hits in the game - The Verge
NFL says positions wearing Guardian Caps saw 52% decrease in concussions - NBC Sports
EXPLAINER: NFL using helmet caps for player safety, research
NFL hopes to reduce head injuries with helmet experiment
The link between head injuries and CTE in football, explained - Vox
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
EXPLAINED: US National Football League Using Helmet Caps For Player Safety, Research - News18
What Pros Wear: Top 5 Helmets Rated by the NFL & NFLPA - What Pros Wear
Future of NFL safety: Inside Vicis' high-tech football helmet production facility in Seattle – GeekWire
This Helmet Will Save Football. Actually, Probably Not. - The New York Times