TROIANO, S., and F. MARANGON. “I Payments for Ecosystem Services a Pro Dal Paisaç E Dal Ambient”. Gjornâl Furlan Des Siencis - Friulian Journal of Science, vol. 15, no. 15, Jan. 2011, pp. 59-67, https://www.gfs-fjs.net/index.php/gsf/article/view/158.