Chris Willis is the head of the Research Library at NFL Films. He is the author of multiple books on early pro football, including The Man Who Built the National Football League: Joe F. Carr (2010), Dutch Clark: The Life of an NFL Legend and the Birth of the Detroit Lions (2012), A Nearly Perfect Season: The Inside Story of the 1984 San Francisco 49ers (2014), and Walter Lingo, Jim Thorpe, and the Oorang Indians: How a Dog Kennel Owner Created the NFL’s Most Famous Traveling Team, all published by Rowman & Littlefield.