1. ADAC, 2007. ADAC Autokosten 2007. URL: http://www.bdb-akbsv.de/zz-webinfo/adac-autokosten-2007.pdf
2. Protected Areas, the Tourist Bubble and Regional Economic Development – Two Case Studies from Mexico and Morocco;Arnegger,2014
3. Australian Government, 2017. National Park. URL: http://www.australia.gov.au/about-australia/australian-story/national-parks (accessed on June 29, 2017)
4. Walk on the wild side: estimating the global magnitude of visits to protected areas;Balmford;PLoS Biol.,2015
5. Economic Valuation of Wetlands: A Guide for Policy Makers and Planners;Barbier,1997