John Madden Football NES prototype? - Prototypes - AtariAge Forums
Let's Play John Madden Football [C64]
What games released pre-2005 are still worth revisiting? - Quora
Throwback Bit Thursday: John Madden Football Games
What games released pre-2005 are still worth revisiting? - Quora
Let's Play John Madden Football [C64]
Madden Football 64 Download - GameFabrique
History of video games/Print version/Fifth Generation of Video Game Consoles - Wikibooks, open books for an open world
John Madden Football (Prototype A) - Hidden Palace
The Untold Truth Of Madden NFL
John Madden Football '93 - Wata 9.6 A++ Sealed, GEN EA Sports 1992, Lot #15811