The Gridiron Uniform Database
List of NFL champions (1920–1969) - Wikipedia
Heritage Uniforms and Jerseys and Stadiums - NFL, MLB, NHL, NBA, NCAA, US Colleges: 2013
The Gridiron Uniform Database
The Gridiron Uniform Database
Early history of American football - Wikipedia
The Gridiron Uniform Database: 1920 and 1921: Before the NFL - The APFA Years
The Gridiron Uniform Database: 1920 and 1921: Before the NFL - The APFA Years
The Gridiron Uniform Database