The Birth of the National Football League
History of the National Football League - Wikipedia
When the College Football Stars Played NFL Champs
NFL Championships History: Has a team ever switched from NFC to AFC?
Inside the New York Giants - Lerner Publishing Group
NFL Rivalries: What is the oldest rivalry in the NFL History?
Baltimore Ravens, History, Facts, & Notable Players
National Football League Record Manual-NFL 1965-226 pages-stats-records-info-VG
Chicago Bears - Wikipedia
Fun fact: no team this past season finished with an 11-6 record : r/nfl
What were the original NFL teams?
National Football Conference - Wikipedia
Super Bowl, History, Appearances, Results, & Facts