GRUEHN, Dietwald. Economic Valuation of Urban Open Spaces and their Contribution to Life Quality in European Cities. Space – Society – Economy, Poland, n. 8, p. 59–66, 2008. DOI: 10.18778/1733-310.08.06. Disponível em: https://www.czasopisma.uni.lodz.pl/space/article/view/22196. Acesso em: 25 may. 2026.