A Look Back at the Super Bowl, and Three Reforms That Are Needed Now - The New York Times
Guardian Cap debuts during minicamps in effort to reduce avoidable head contact
Helmet Innovation: More and Better Choices, Fewer Concussions
The Evolution of Football Helmets: From Leather to Carbon Fiber
Large Bubble Helmets Are Guardian Caps, NFL's New Safety Measure
Guardian Cap Debuts at Training Camps League-wide
Tracking how high school football helmets are inspected and refurbished each year
NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets
The N.F.L. Struggles to Tackle Its Latest Problem: Tackling - The New York Times
Built By Data: NFL Helmet Innovation