Exploring User-Generated Content for Improving Destination Knowledge: The Case of Two World Heritage Cities Sustainability Journal Article Nuno Antonio Marisol Correia Filipa Ribeiro Publication Year of Publication: 2020 Volume: 12 Issue: 22 Pagination: 9654 Identifiers Locators URL https://doi.org/10.3390/su12229654 DOI: 10.3390/su12229654 Sustainable Development Goals