AVASTHI, T. P. An Introduction to GIS. The Third Pole: Journal of Geography Education, [S. l.], v. 5, p. 76–78, 2009. DOI: 10.3126/ttp.v5i0.1957. Disponível em: https://www.nepjol.info/index.php/TTP/article/view/1957. Acesso em: 7 may. 2024.