First QB helmet designed to help reduce concussions, Sports
Football Turns to Helmet Technology to Tackle Head Injuries
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
Football helmets have improved but are far from 'concussion proof' – Orange County Register
Guardian Caps Guardian Sports
NFL hopes to reduce head injuries with helmet experiment
New helmet design can deal with sports' twists and turns
Football Concussions: Prevention, Diagnosis & Recovery
Dallas-Fort Worth high school helmets and concussions
What Pros Wear: Top 5 Helmets Rated by the NFL & NFLPA - What Pros Wear