NFL to test new position-specific helmet designed for linemen
Montreal-based consortium one of three winners of NFL helmet safety challenge
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
Football Helmet Testing, Technology and Safety Research
Guardian Caps Guardian Sports
Impact test comparisons of 20th and 21st century American football helmets in: Journal of Neurosurgery Volume 116 Issue 1 (2012) Journals
With concussions at forefront of minds, helmet designs more important
Watch NBC Nightly News With Lester Holt Excerpt: NFL
NCAA football helmets: Is style jeopardizing player safety?
This Startup's 2 Helmets Are Officially the Safest in Football, According to the NFL