Old School: Leatherhead Football Helmets Worked As Well As Modern Ones
Antiques: Football helmets across the decades
Applied Sciences, Free Full-Text
Delaware State University Archives and Special Collections: Helmets Through History
The Football Helmet timeline
Applied Sciences, Free Full-Text
The Evolution of Football Helmets
Interesting WWII/Post War Flight Helmet Id'd - FLYING HELMETS AND ACCESSORIES - U.S. Militaria Forum
A Short History of American Football Helmets - HubPages