Find out how modern football helmets attempt to limit brain injuries
Riddell's Axiom could be breakthrough helmet for football
Are Modern Football Helmets Any Safer than Old-School Leather Ones?, Science
EXPLAINER: NFL using helmet caps for player safety, research - The San Diego Union-Tribune
What are Guardian Caps? NFL players sport specialty helmets for 2022 minicamp
Virginia Tech research provides much-needed data, system for rating sports equipment - ESPN
Padded helmet cover shows little protection for football players - Scope
Guardian Caps Guardian Sports
NFL downgrades safety of 9 helmet models used by 18 percent of players - The Athletic
New Smart Helmet Could Spot Concussions in Real Time
Seeking to reduce head contact, NFL mandates use of Guardian Cap helmet for early portion of training camp - ESPN
Guardian Caps Guardian Sports
Why are NFL players wearing padding on helmets at training camp?