N661US - Wikipedia,The World's First 747-400 To Fly Last Revenue Flight, Leaving a Legacy Behind | AirlineGeeks.com,The World's First 747-400 To Fly Last Revenue Flight, Leaving a Legacy Behind | AirlineGeeks.com,Info on this Airframe - DA.C,Northwest Airlines' first Boeing 747-400 retires at Delta museum (Photos and Video) - Minneapolis / St. Paul Business Journal