GALLATLY, W. The Polar Circle. The Journal of the Indian Mathematical Society, [S. l.], v. 4, n. 3, p. 91–92, 1912. DOI: 10.18311/jims/1912/17755. Disponível em: https://informaticsjournals.com/index.php/jims/article/view/17755. Acesso em: 29 mar. 2024.