Virginia Tech research provides much-needed data, system for rating sports equipment - ESPN
Building a better helmet - The Globe and Mail
Are Modern Football Helmets Any Safer than Old-School Leather Ones?, Science
NFL testing safer helmets
History of the NFL Helmet
The Football Helmet Just Got the Biggest Redesign Since the 1960s--and It's Coming to the NFL Next Season
VICIS Innovation Continues ZERO1 Top Ranked in NFL testing for 2018 season- NFL bans several underperforming helmets for 1st time
The Cleveland Browns and NFL's Alternate Helmets in 2022
Why are NFL players wearing padding on helmets at training camp?
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post