Wake Up Washington Commanders adjust to guardian caps at first practice of training camp
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
Guardian Caps Exceed NFL's Expectations - Guardian Sports
NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets
For Giants and the NFL, it's the Summer of Guardian Caps - Newsday
NFL expands rule against misuse of helmet; Guardian Caps required in regular season, postseason
EXPLAINER: NFL using helmet caps for player safety, research - The San Diego Union-Tribune
NFL Health and Safety Fact Sheet
Los Angeles Rams Support NFL Mandated Guardian Caps - Sports Illustrated LA Rams News, Analysis and More