MCKNIGHT, T. L. Great Circles on the Great Plains: The changing geometry of american agriculture. ERDKUNDE, [S. l.], v. 33, n. 1, p. 70–79, 1979. DOI: 10.3112/erdkunde.1979.01.08. Disponível em: https://www.erdkunde.uni-bonn.de/article/view/1869. Acesso em: 28 oct. 2025.