HALL, T. D. Puzzles in the Comparative Study of Frontiers: Problems, Some Solutions, and Methodological Implications. Journal of World-Systems Research, [S. l.], v. 15, n. 1, p. 25–47, 2009. DOI: 10.5195/jwsr.2009.332. Disponível em: http://jwsr.pitt.edu/ojs/jwsr/article/view/332. Acesso em: 24 feb. 2024.