U.V Jose and  Muhammed Nahar and  Vijayakumar S. and  Sonia Jose,  Balancing Tourism and Environment: The ETM Model.   journal   = {International Journal of Humanities and Social Sciences}, [online]. World Academy of Science, Engineering and Technology.
    June 2009, vol. 30(6). 1147 - 1152
    [viewed 23 January 2020]. Available from: https://publications.waset.org/pdf/9758.