Man Who Built the National Football LeagueChris Willis, James A. Carr · First published 2010Open the Tome
2008 Official playing rules of the National Football LeagueNational Football League · First published 2008Open the Tome
Official National Football League record & fact bookNational Football League · First published 1992Open the Tome
The official National Football League football encyclopediaRoger L. Treat · First published 1952Open the Tome
