2017 the UN International Year of Sustainable Tourism for Development.

http://media.unwto.org/press-release/2015-12-07/united-nations-declares-2017-international-year-sustainable-tourism-develop

https://www.theguardian.com/sustainable-business/sustainable-tourism-10-key-issues-investors

http://www.sesric.org/files/article/127.pdf

https://sustainabledevelopment.un.org/content/documents/12023Kulshreshtha.pdf

http://www.helsinki.fi/henvi/yvv/esitykset/janis.pdf

http://www.unep.org/10yfp/programmes/sustainable-tourism-programme

http://sdt.unwto.org/content/about-us-5

mass tourism and the damage it causes

http://veneziaautentica.com/why-tourism-in-venice-is-doing-more-harm-than-good-and-what-we-can-do-about-it/