FOX Sports: NFL on X: There's only been ONE season where fewer undefeated teams headed into Week 4 1972, when the #Dolphins had a perfect season. / X
50 years on, the 1972 Miami Dolphins' undefeated season remains undefeated, Miami Dolphins
NFL - There's only one team to ever do it. #72Dolphins 50
NFL on X: 50 years later, there's still only one perfect team. #72Dolphins @MiamiDolphins
1972 Miami Dolphins: The inside story of the only perfect season in NFL history
50 years later, '72 Dolphins remain unmatched in perfection
NFL teams that came closest to going undefeated, joining the 1972 Dolphins as members of the perfect club
1972 Miami Dolphins remain only undefeated team in NFL History - The Phinsider
Eagles not undefeated anymore: Has there ever been a perfect season in the NFL? - AS USA