BIRKMANN, Jörn. Indicators of sustainable development: The cornerstones of an indicator system for spatial-Planning issues at local-authority level. Raumforschung und Raumordnung | Spatial Research and Planning, DE, v. 57, n. 2-3, p. 120–131, 1999. DOI: 10.1007/BF03184482. Disponível em: https://rur.oekom.de/index.php/rur/article/view/1072. Acesso em: 15 aug. 2026.