1. Costanza R, d’Arge R, de Groot R, Farber S, Grasso M, Hannon B, et al. The value of the world’s ecosystem services and natural capital. Nature. 1997;387:253–60.
2. Dudgeon D, Arthington AH, Gessner MO, Kawabata ZI, Knowler DJ, Leveque C, et al. Freshwater biodiversity: importance, threats, status and conservation challenges. Biol Rev. 2006;81:163–82.
3. Vörösmarty CJ, Lévêque C, Revenga C, Bos R, Caudill C, Chilton J, et al. Fresh water. In: Hassan R, Scholes R, Ash N, editors. Ecosystems and human well-being: current state and trends. Millennium ecosystem assessment, V. 1. Washington, DC: Island Press; 2005.
http://www.millenniumassessment.org/documents/document.276.aspx.pdf
. Accessed 19 Oct 2017.
4. Millennium Ecosystem Assessment. Ecosystems and human well-being: wetlands and water synthesis. Washington, DC: World Resources Institute; 2005.
http://www.millenniumassessment.org/documents/document.358.aspx.pdf
. Accessed 19 Oct 2017
5. Lehner B, Döll P. Development and validation of a global database of lakes, reservoirs and wetlands. J Hydrol. 2004;296:1–22.