1. Baral, N., M.J. Stern, and A.L. Hammett. 2012. Developing a scale for evaluating ecotourism by visitors: A study in the Annapurna Conservation Area, Nepal. Journal of Sustainable Tourism 20(7): 975–989.
2. Baretje, R. 1977. Tourist carrying capacity. Essai Bibliographiques, Essais 1. Aix-en-Provence: Cente des Hautes Etudes Touristiques.
3. Bossel, H. 1999. Indicators for sustainable development: Theory, methods, applications. Winnipeg: International Institute for Sustainable Development.
4. Boyd, S.W. 2002. Tourism, national parks and sustainability. In Tourism and national parks, issues and implication, ed. R.W. Butler and S.W. Boyd. New York: Wiley.
5. Broson, J., and B. Noble. 2006. Measuring the effectiveness of Parks Canada’s environmental management system. The Canadian Geographer 50(1): 101–113.