SUNTUM, Ulrich van. Purchasing-power flows in retailing: A forecasting model based on gravitation theory. Raumforschung und Raumordnung | Spatial Research and Planning, DE, v. 58, n. 6, p. 448–456, 2000. DOI: 10.1007/BF03182990. Disponível em: https://rur.oekom.de/index.php/rur/article/view/1179. Acesso em: 17 may. 2025.