Estima, D., M. Ventura, A. Rabinovici, and F. P. F. Martins. “Constraints and Contributions of Environmental Non-Governmental Organizations for the Sustainability of Tourism on Islands: A Case Study from the Azores Archipelago, Portugal.”. Journal of Tourism & Development, Vol. 1, no. 27/28, Jan. 2017, pp. 1627-3, doi:10.34624/rtd.v1i27/28.10183.