2013 Army Football Guide by Army West Point Athletics - Issuu
2019 Northwestern State Football Media Guide by Northwestern State Sports Information - Issuu
NFL History: 100 objects that tell the story of football - Sports Illustrated
NFL Flag San Diego Switches to GameBreaker Helmets to Enhance Player Safety
Nick Canepa's report card: Justin Herbert gets an A+ for Sunday's win. Coaching? Not so much. - The San Diego Union-Tribune
New helmet design can deal with sports' twists and turns
2014 Northwestern State Football Media Guide by Northwestern State Athletics - Issuu
NFL Health and Safety Related Rules Changes Since 2002
Explanation: NFL using helmet caps for player safety, research
Chargers News: NFL, NFLPA approves first-ever position-specific helmets - Bolts From The Blue
Guardian Caps: Why some NFL players are wearing them in training camps
Chargers OTAs: Justin Herbert on target; defense beefed up - The San Diego Union-Tribune