Chardon (1980), стр. 142, 144, & 151. Chardon, Roland (1980), „The Linear League in North America”, Annals of the Association of American Geographers, 70 (2), Association of American Geographers, Taylor & Francis, стр. 129—153, JSTOR2562946, doi:10.1111/j.1467-8306.1980.tb01304.x.
Chardon (1980), стр. 142, 144, & 151. Chardon, Roland (1980), „The Linear League in North America”, Annals of the Association of American Geographers, 70 (2), Association of American Geographers, Taylor & Francis, стр. 129—153, JSTOR2562946, doi:10.1111/j.1467-8306.1980.tb01304.x.