The Indian Dog Train Was Used When the Snow Was Too Deep or Too Soft to Uphold Horses (1915)

Seymour Dunbar, A History of Travel in America, Showing the Development of Travel and Transportation from the Crude Methods of the Canoe and the Dog-Sled to the Highly Organized Railway Systems of the Present, Together with a Narrative of the Human Experiences and Changing Social Conditions That Accompanied This Economic Conquest of the Continent  (Indianapolis: The Bobbs-Merrill Company, 1915), 54.