Damar Hamlin and Sam Peltzman: Where Football Meets Economics - Econlib
Guardian Caps: Why some NFL players are wearing them in training camps
What are Guardian Caps? NFL's latest padded helmets for added safety
The epidemic of concussions in the NFL - The Paisano
Guardian Caps Exceed NFL's Expectations - Guardian Sports
Kiski Area football adds Guardian Caps for extra level of safety during practice
These puffy helmet caps are the next big thing in NFL player safety, National Sports
What is a Guardian Cap? Meet the NFL's newest safety measure
Coverage of the NFL in Guardian Caps
Seeking to reduce head contact, NFL mandates use of Guardian Cap helmet for early portion of training camp - ESPN
Could Guardian Caps be used during NFL games for player safety?, Pro Football Talk
A closer look at the rule changes the NFL is debating - The Washington Post
Coverage of the NFL in Guardian Caps