NFL hopes to reduce head injuries with helmet experiment, FOX 4 Kansas City WDAF-TV
Protective helmets make sports safer
How New Helmet Technology Will Make the NFL and NHL Safer, News, Scores, Highlights, Stats, and Rumors
Impressio, CU Denver making safer football helmets with NFL grant - CU Denver News
What Pros Wear: Top 5 Helmets Rated by the NFL & NFLPA - What Pros Wear
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
NFL testing 3D printed helmets from Carbon, Peyton Manning excited
NFL takes first-ever step to ban some helmets after testing - The San Diego Union-Tribune
NFL, NFLPA ban 10 helmet models after failing testing
NFL-Funded Lab Building a Safer Football Helmet
NFL to test new position-specific helmet designed for linemen