GRABOWSKY, A. Geopolitik und Geographie. ERDKUNDE, [S. l.], v. 16, n. 3, p. 216–219, 1962. DOI: 10.3112/erdkunde.1962.03.05. Disponível em: https://www.erdkunde.uni-bonn.de/article/view/1390. Acesso em: 17 may. 2025.