Helmet sensors become mandatory equipment in Arena Football League
League of Denial: The NFL, Concussions and the Battle for Truth by Mark Fainaru-Wada
The Tragic Risks of American Football
Nevius: NFL wants to go global, but will it translate?
NFL report: concussions dropped 50 PERCENT when players wore new 'Guardian Caps' over the summer
Flexible NFL helmet aims to reduce head injuries
Tracing the Evolution of Player Safety Throughout NFL History, News, Scores, Highlights, Stats, and Rumors
Built By Data: NFL Helmet Innovation
Football helmets are creating more problems than they solve
N.F.L. Will Allow Six Social Justice Messages on Players' Helmets - The New York Times
Health and Safety Related Changes for the 2018 Season
How NCAA Football Can Finally Limit Concussions - Global Sport Matters
SC Johnson provides money for football helmets, concussion-screening