Delaware State University Archives and Special Collections
The Evolution of Football Helmets, by Jose Diaz
The History of The Football Helmet timeline
Design and Virtual Testing of American Football Helmets–A Review
Delaware State University Archives and Special Collections
History of The Football Helmet - Atavus
Protected Development: A Century of Football-Helmet Innovation
Researchers test old-style leather helmets vs. modern ones and
Impact test comparisons of 20th and 21st century American football
Leatherhead to Radio-head: The Evolution of the Football Helmet
History of The Football Helmet - Atavus