How to connect a trailer plug if you don't know the wire colors - YouTube
How to Install Trailer Wiring | U-Haul
Trailer Wiring Care | BoatUS
How to Wire Trailer Lights : 9 Steps (with Pictures) - Instructables
Dr Infrared Heater 6 ft. 7-Way Trailer Plug Cord Wiring Harness, Heavy-Duty Weatherproof, Corrosion Resistant Inline Cable, for RV, Campers DR-RV106 - The Home Depot