1. Arachchi, R. S. S. W., Yajid, M. S. A., & Khatibi, A. (2015). Ecotourism practices in Sri Lankan eco resorts: A supplier perspective analysis. Journal of Tourism and Hospitality Management, 3(9-10), 169-180. DOI: 10.17265/2328-2169/2015.10.001;
2. Batta, R. N. (2006). Evaluating ecotourism in mountain areas: A study of three Himalayan destinations. International Review for Environmental Strategies, 6(1), 41-62.;
3. Beaumont, N. (2011). The third criterion of ecotourism: Are ecotourists more concerned about sustainability than other tourists?. Journal of Ecotourism, 10(2), 135-148. DOI: 10.1080/14724049.2011.555554.;
4. Blamey, R. K. (2001). Principles of ecotourism. The encyclopedia of ecotourism, 2001, 5-22.;
5. Blangy, S., & Vautier, S. (2001). Europe. In D. B. Weaver (Ed.), The Encyclopedia of Ecotourism (pp. 155-171), Oxon, UK, CAB International.;