HARD, Gerhard. Die Kompetenz des Geographen. Journal of Geography Education, [S. l.], v. 7, n. 3, p. 141–151, 1979. DOI: 10.60511/zgd.v7i3.445. Disponível em: https://zgd-journal.de/index.php/zgd/article/view/445. Acesso em: 2 apr. 2026.