Deborah M. Stultz (1979). The Red River Trails: Oxcart Routes Between St. Paul and the Selkirk Settlement, 1820-1870. St. Paul: Minnesota Historical Society
the historical cartography of the United States. Baltimore, Maryland: The Johns Hopkins Press. {{cite book}}: (עזרה) Cox, Isaac Joslin (1918). The West
ISBN 0-691-14021-9. Crutchfield, Steve (12 באוקטובר 2010), "The Joy of Convolution", Johns Hopkins University, נבדק ב-21 בנובמבר 2010 {{citation}}: (עזרה) Vaidyanathan