Martins, José R. S. «How to Find the Lower Altitude of a Region Using a Pair of Aerial Photography?». Terræ Didatica 14, no. 4 (diciembre 7, 2018): 427–430. Accedido julio 17, 2024. https://periodicos.sbu.unicamp.br/ojs/index.php/td/article/view/8654192.