The jungle frontier: interpretation of Machupicchu and other fortresses bordering the forested region of America as climatic and penitential colonies. Letras, Lima, Peru, v. 4, n. 9, p. 51–59, 1938. DOI: 10.30920/letras.4.9.4. Disponível em: https://revistaletras.unmsm.edu.pe/index.php/le/article/view/1253. Acesso em: 13 sep. 2026.